Maintaining an Authenticated State

ABSTRACT

This document describes techniques and systems for maintaining an authenticated state based radar data from a radar system, and in some cases, on sensor data from an Inertial Measurement Unit (IMU). The techniques and systems use radar data to determine, after an indication that the user has potentially disengaged with the user equipment, to determine whether or not the user is passively engaged with the user equipment. Responsive to determining that the user is passively engaged, the techniques and systems maintain the authenticated state. By maintaining this authenticated state, the techniques manage the user equipment&#39;s state to correspond to a user&#39;s engagement with the user equipment, which can save power and improve a user&#39;s experience.

RELATED APPLICATIONS

This application is a continuation of and claims priority to PCT PatentApplication Serial No. PCT/US2019/049208 filed Aug. 30, 2019 entitled“Maintaining an Authenticated State”, which, in turn, claims priorityunder 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No.62/879,361, entitled “Authentication Management Using IMU and Radar” andfiled on Jul. 26, 2019, the disclosures of which are incorporated intheir entireties by reference herein.

BACKGROUND

User equipment, such as smartphones, wearable computers, and tablets,often require authentication of a user prior to permitting access to thedevice. Once the user equipment has authenticated the user, the userequipment enters an authenticated state in which the user enjoys accessto various data, applications, and functions of the user equipment.

As users interact with their devices more and more often, with someusers authenticating themselves to their devices tens or even hundredsof times a day, the importance of managing this authenticated statecontinues to rise. Any error in managing this authenticated state, suchas failing to remain authenticated when a user wishes to maintain accessor failing to de-authenticate when appropriate, is increasinglyproblematic.

SUMMARY

This document describes techniques and systems for maintaining anauthenticated state. The techniques and systems use radar data, and insome cases inertial sensor data from an inertial measurement unit (IMU),to determine when to maintain an authenticated state, thereby permittinga user to maintain access to their user equipment when some currenttechniques would de-authenticate the user. These techniques and systemsconserve power, improve a user's experience, or better protect a user'sprivacy.

For example, a method is described that determines, during anauthenticated state of a user equipment, a potential disengagement bythe user of the user equipment. This authenticated state permits accessby the user of data, applications, functions, accounts, or components ofthe user equipment. The method also determines, based on radar data andby the user equipment, a passive engagement by the user with the userequipment. Responsive to the determination of the passive engagement bythe user with the user equipment, the method maintains the authenticatedstate.

This document also describes computer-readable media having instructionsfor performing the above-summarized method and other methods set forthherein, as well as systems and means for performing these methods.

This summary is provided to introduce simplified concepts formaintaining an authenticated state, which is further described below inthe Detailed Description and Drawings. This summary is not intended toidentify essential features of the claimed subject matter, nor is itintended for use in determining the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The details of one or more aspects of maintaining an authenticated stateare described in this document with reference to the following drawings.The same numbers are used throughout the drawings to reference likefeatures and components:

FIG. 1 illustrates an example environment in which techniques formaintaining an authenticated state can be implemented.

FIG. 2 illustrates an example of the authentication system set forth inFIG. 1.

FIG. 3 illustrates an example user authenticated by the authenticationsystem of FIG. 2.

FIG. 4 illustrates an implementation of the user equipment of FIG. 1that can alter states, including a power state of an authenticationsystem responsive to determination of a user's intent to engage with auser equipment.

FIG. 5 illustrates example information, power, and access states of auser equipment.

FIG. 6-1 illustrates an example radar system as part of a computingdevice.

FIG. 6-2 illustrates an example transceiver and processor.

FIG. 6-3 illustrates an example relationship between power consumption,a gesture-frame update rate, and a response delay.

FIG. 6-4 illustrates an example framing structure.

FIG. 7 illustrates example arrangements of receiving antenna elementsfor the radar system of FIG. 6-1.

FIG. 8 illustrates additional details of an example implementation ofthe radar system of FIG. 6-1.

FIG. 9 illustrates an example scheme that can be implemented by theradar system of FIG. 6-1.

FIG. 10 illustrates an example method for authentication managementthrough IMU and/or radar.

FIG. 11 illustrates an example scenario for authentication management.

FIG. 12 illustrates an example method for reducing a state of a userequipment.

FIG. 13 illustrates an example scenario for reducing a state of a userequipment.

FIG. 14 illustrates an example method for maintaining an authenticatedstate.

FIG. 15 illustrates an example scenario for maintaining an authenticatedstate.

FIG. 16 illustrates another example scenario for maintaining anauthenticated state.

DETAILED DESCRIPTION

Overview

This document describes techniques and systems for maintaining anauthenticated state based radar data from a radar system, and in somecases, on sensor data from an Inertial Measurement Unit (IMU). Thetechniques and systems use radar data to determine, after an indicationthat the user has potentially disengaged with the user equipment, todetermine whether or not the user is passively engaged with the userequipment. Responsive to determining that the user is passively engaged,the techniques and systems maintain the authenticated state. Bymaintaining this authenticated state, the techniques manage the userequipment's state to correspond to a user's engagement with the userequipment, which can save power and improve a user's experience.

Furthermore, alternative techniques are disclosed that de-authenticatethe user equipment responsive to a non-user's presence or intent toengage with the user equipment, thereby reducing unwarranted access,reducing an amount of information provided to a non-user, both of whichcan help protect the user's privacy.

In contrast to the disclosed techniques, conventional user equipment areoften unable to accurately determine a user's engagement with the userequipment (UE). Because these UE are unable to do so, but still need tode-authenticate the UE to keep it secure, current techniques lock the UEwhen a time period expires. This time period, for many conventionaltechniques, is a period during which the user has not pressed anybuttons or touched a sensor on the mobile device, such as touching atouch-sensitive display. Thus, conventional techniques often start atimer when no obvious input from a user is received, and thende-authenticate the UE when the timer expires without any obvious input.But this solution can de-authenticate a user when that user stilldesires to maintain engagement with, or at least maintain theauthenticated state of, the user equipment. Because current solutionsde-authenticate when undesired by the user, the user's experience isreduced by having to re-authenticate and power is wasted in performingthe re-authentication.

By way of one example, assume that a user, while their tablet computeris in an authenticated state, sets their tablet against a book on theirdesk, selects a movie to watch, and then sits back to watch the movie.Conventional techniques often start a timer, and then, after the timerexpires without any obvious input from the user, de-authenticates theuser equipment. If, as is common, the time period is five minutes, theuser's device then de-authenticates (e.g., “locks”). If the user wishesto access the user device, they must re-authenticate. This provides apoor user experience and wastes power, often resulting in reducedbattery life, further reducing the user's experience with their userequipment.

In contrast to these conventional techniques, the described techniquesdetermine, based on radar data, that a user is passively engaged withthe user equipment, such as by determining that they are continuing tolook toward the tablet computer. Based on this passive engagement, thetechniques maintain the authenticated state, thereby permitting the userto access the user equipment without re-authenticating.

This is but one example of how the described techniques and devices maybe used to maintain an authenticated state. Other examples andimplementations are described throughout this document. The document nowturns to an example operating environment, after which example devices,methods, and systems are described.

Operating Environment

FIG. 1 illustrates an example environment 100 in which techniques formaintaining an authenticated state can be implemented. The exampleenvironment 100 includes a user equipment (UE) 102 (e.g., a smartphone),which includes, or is associated with, a radar system 104, a radarmanager 106, an inertial measurement unit (IMU) 108, a movement manager110, a state manager 112, an authentication system 114, and a display116.

In the example environment 100, the radar system 104 provides a radarfield 118 by transmitting one or more radar signals or waveforms asdescribed below with reference to FIGS. 7-9. The radar field 118 is avolume of space from which the radar system 104 can detect reflectionsof the radar signals and waveforms (e.g., radar signals and waveformsreflected from objects in the volume of space, also referred togenerally herein as radar data). The radar system 104 also enables theUE 102, or another electronic device, to sense and analyze this radardata from reflections within the radar field 118. The radar field 118may take any of a variety of shapes and forms. For example, the radarfield 118 may have a shape as described with reference to FIGS. 1 and 7.In other cases, the radar field 118 may take a shape of a radiusextending from the radar system 104, a volume around the radar system104 (e.g., a sphere, a hemisphere, a partial sphere, a beam, or a cone),or a non-uniform shape (e.g., to accommodate interference fromobstructions in the radar field 118). The radar field 118 may extend anyof a variety of distances from the radar system 104 such as inches totwelve feet (less than a third of a meter to four meters). The radarfield 118 may be predefined, user-selectable, or determined via anothermethod (e.g., based on power requirements, remaining battery life, oranother factor).

The reflection from the user 120 in the radar field 118 enables theradar system 104 to determine various information about the user 120,such as the body position and posture of the user 120, which mayindicate a variety of different nonverbal body language cues, bodypositions, or body postures. The cues, positions, and postures mayinclude an absolute position or distance of the user 120 with referenceto the UE 102, a change in the position or distance of the user 120 withreference to the UE 102 (e.g., whether the user 120 or the user's handor object held by the user 120 is moving closer to or farther from theUE 102), the velocity of the user 120 (e.g., a hand or a non-userobject) when moving toward or away from the UE 102, whether the user 120turns toward or away from the UE 102, whether the user 120 leans toward,waves toward, reaches for, or points at the UE 102, and so forth. Thesereflections can also be analyzed to determine, or to add confidence to,authentication, such as an identity of a human through analysis of theradar data (e.g., scattering centers of a user's face).

The radar manager 106 is configured to determine, based on radar datafrom the radar system 104, a user's intent to engage, disengage, ormaintain engagement with the UE 102. A user's intent can be deduced fromthe various cues, positions, postures, and distances/velocities notedabove, such as based on a hand or arm reach toward, a movement of eyesto look at, or movement of a head or face oriented toward the UE 102.For a hand or arm reach, the radar manager 106 determines that the useris reaching their hand or orienting their arm in such a way as toindicate a likely intent to touch or pick up the UE 102. Examplesinclude a user reaching toward a volume button on a wirelessly attachedspeaker, a reach toward a wireless or wired mouse associated with atablet computer, or a reach toward the UE 102 itself This reach towardcan be determined based on a hand movement alone, an arm and handmovement, or an arm bending or straightening in a manner that permits ahand of the arm to touch or grab the UE 102. As noted in FIGS. 14-16below, this intent to engage determination can be for non-users orusers, authenticated or not.

A user's intent to engage can also be deduced based on a user's movementof their head or eyes to look at, or orient their face toward, the UE102 or, in some cases, an associated peripheral of the UE 102. Formovement of a user's eyes to look toward the UE 102, the radar manager106 determines that the user's eyes are looking in the direction of theUE 102, such as through tracking of the user's eyes. For movement of theuser's head to orient their face toward the UE 102 (e.g., a facialorientation), the radar manager 106 determines that various points(e.g., scattering centers as noted below) are now oriented such that theuser's face is pointing toward the UE 102. Thus, a user need not performan action designed to control or activate the UE 102, such as activating(pressing) on a button on the UE 102, or a touch-dependent gesture(e.g., on a touch pad or screen) or touch-independent gesture (e.g.,using the radar system 104) in order for the radar manager 106 todetermine that the user intends to engage (or disengage or maintainengagement) with the UE 102.

As noted above, the radar manager 106 is also configured to determine auser's intent to disengage with the UE 102. The radar manager 106determines a user's intent to disengage similarly to a user's intent toengage, though deduced from radar data indicating that the user's handor arm is moving away from the UE 102 (e.g., retracting), movement ofeyes to look away from, or movement of the head or face away from the UE102 (e.g., a facial orientation change away from looking at the UE 102).Additional manners through which to determine a user's intent todisengage are not only the opposite or cessation of engagement notedabove, but also radar data indicating that the user has walked away,moved their body away from, or has engaged with a different,unassociated object or device. Thus, the radar manager 106 may determinean intent to disengage with the UE 102 based on determining an intent toengage, by the user, with some other object, device, or user equipment.Assume, for example, that a user is looking at and interacting with asmartphone. Example intents to engage that indicate an intent todisengage with that smartphone include the user looking, instead of atthe smartphone, at a television screen, beginning to talk to a nearbyphysically-present person, or reaching toward another device with whichengagement is likely to replace the engagement with the smartphone, suchas an e-book or media player.

The radar manager 106 is also configured to determine a user's intent tomaintain engagement with the UE 102. This maintaining of engagement canbe active or passive. For active engagement, the radar manager 106 maydetermine, based on radar data, that the user is interacting throughtouch-independent gestures, and so forth. The radar manager 106 may alsoor instead determine active engagement through non-radar data (e.g.,performed with assistance from other components of the UE 102). Thesenon-radar data include indications that the user is inputting data to orcontrolling the UE 102 or a peripheral. Thus, through touch, typing, oraudio data, the user is determined to be touching (e.g., tapping on asoft keyboard or performing a gesture) through a touch-screen input ofthe display 116, typing on a peripheral keyboard, or is determined to bedictating an audio input. For maintaining passive engagement, the radarmanager 106 determines, independently or through assistance of othercomponents of the UE 102, that the user is consuming content orproviding the UE 102 to others to consume content, such as pointingtheir face toward the UE 102, looking at the display 116, or is holdingthe UE 102 in such a way as to orient the UE 102's display to be visibleby the user or a third party. Other examples of maintaining passiveengagement include a user's presence, such as through the radar manager106 determining that the user 120 is within reach of (e.g., two, 1.5,one, or one-half of one meter from) the UE 102. Details of example waysin which the radar manager 106 determines a user's intent to engage,disengage, or maintain engagement, both passively and actively, aredescribed below.

Further still, the radar manager 106, using radar data from the radarsystem 104, may also determine gestures performed by a user. Thesegestures can involve the user touching some surface, such as a table,the display 116, or their shirt sleeve, or touch-independent gestures.Touch-independent gestures can be performed in the air, in threedimensions, and/or without necessitating a hand or fingers touch aninput device, but are not precluded from touching some object. Thesegestures can be determined based on the radar data and then used asinput to, or to indicate engagement with, the UE 102. Example gesturesinclude those similar to sign language (e.g., ASL or American SignLanguage), which are varied, complex single hand or multi-hand gestures,or simple multi-hand or single hand gestures, such as to swipe left,right, up, or down, flat-hand-raise or lower (e.g., to raise or lowermusic volume of the UE 102 or a television or stereo controlled throughthe UE 102), or to swipe forward or backward (e.g., left-to-right orright-to-left) to change music and video tracks, snooze alarms, dismissphone calls, or even play games. These are but a few of the many examplegestures and functions controllable by these gestures and which areenabled through the radar system 104 and the radar manager 106. Thus,while this document is directed to engagement and state management,nothing in this document should be misconstrued to indicate that theradar system 104 and the radar manager 106 cannot also be configured forgesture recognition.

The IMU 108 can be any of a variety of devices configured to measuremovement, which is here defined to include specific force, angular rate,orientation, vibrations, acceleration, velocity, and position, includingpitch, roll, and yaw for each of three axes (e.g., X, Y, and Z). The IMU108 can be one or multiple devices within the UE 102, such as anaccelerometer, gyroscope, and/or magnetometer.

The movement manager 110 is configured to determine, based on inertialdata from the IMU 108, movements of the UE 102. Example movementsinclude the UE 102 being lifted (e.g., picked up), oriented toward oraway from the user 120, and vibrations. Example movements can indicatecessation of physical contact by the user 120 of the UE 102, placementof the UE 102 on a non-living object (e.g., a table, car console, coucharm, pillow, floor, docking station), and placement of the UE 102 withinan enclosed container, e.g., a pocket, bag, or purse.

These movements can indicate a user's potential engagement,disengagement, or maintained engagement with the UE 102. For example,the movement of the UE 102 may indicate that the user equipment ismoving or orienting toward or is being moved/oriented away from the user120, is moving too rapidly or changing movement too rapidly to beinteracted with for many likely types of user engagement, is being heldby the user 120 (via natural human movements, respiration, heartbeat),or is vibrating due to a mechanical or non-user source (e.g., avehicle's vibration, ambient sounds shaking the UE 102, music causingthe UE 102 to vibrate). Thus, orienting away, which would indicate apotential disengagement with the UE 102, may include an orientationchange of the UE 102 such that a prior orientation where the user 120was likely to have been looking at the display 116, is now unlikely tobe doing so. The user 120 typing or reading at one orientation, and thenturning the phone over, or sideways, or placing in a pocket, etc., isbut one example of a movement indicating an orienting away and thus apotential disengagement. Example movements that may indicate maintainedengagement include vibrations indicating that a user is maintaining ahold or placement of the UE 102 or is maintaining their orientationrelative to the UE 102 where that orientation previously indicated, orwas coincident with, engagement with the UE 102.

The display 116 can include any suitable display device, such as atouchscreen, a liquid crystal display (LCD), thin film transistor (TFT)LCD, an in-place switching (IPS) LCD, a capacitive touchscreen display,an organic light emitting diode (OLED) display, an active-matrix organiclight-emitting diode (AMOLED) display, super AMOLED display, and soforth. As noted, the display 116 can be powered at various levels, suchas at full saturation with touch-input powered, reduced saturationwithout touch-input powered, and with low-saturation and low power(e.g., a gray clock) or no power.

The state manager 112 manages states of the UE 102, such as power,access, and information states. This management of the UE 102 and itscomponents is performed based on determinations made by the radarmanager 106 and the movement manager 110. For example, the state manager112 can manage powering a component of the authentication system 114,such as by altering the UE 102's display 116 to increase power inanticipation of receiving touch input from the user 120 to input apassword, a computer processor to perform calculations used inauthentication, or an imaging system to perform image-based facialauthentication, radar (e.g., the radar system 104), or other components.

As noted, this managing of the UE 102 is based on determinations by theradar manager 106 and the movement manager 110, which determine anintent to engage, disengage, or maintain engagement and movement of theUE 102, respectively. The state manager 112 can do so based on thesedeterminations alone or also based on other information, such as acurrent state, current engagement, applications running and the contentshown by these applications, and so forth. Furthermore, while the radarmanager 106 may determine a user's intent and the movement manager 110can determine movement, some of which are determined to indicate auser's intent to engage with the UE 102, the state manager 112, by usingboth of their determinations, can improve the accuracy, robustness,and/or speed of an overall determination that the user's intent is toengage, disengage, or maintain engagement with the UE 102.

This use of both determinations, that of the radar manager 106 and themovement manager 110, can be performed together or in stages as part ofmanaging the states of the UE 102, or one of these may alone be used.For example, assume that the UE 102 is at a low-power state forcomponents used to authenticate. The radar manager 106 may determinethat the user 120 is intending to authenticate with the UE 102 based ona movement toward or a reach toward the UE 102. In some cases this aloneis considered by the state manager 112 to be insufficient for the statemanager 112 to cause the UE 102 to be altered to a high-power state.Thus, the state manager 112 can cause some of the authenticationcomponents to be powered up to an intermediate state, rather than ahigh-power state (e.g., the high-power state 504-1 of FIG. 5). Forexample, in cases where the authentication system 114 uses infraredsensors to perform facial recognition, the state manager 112 can powerthese sensors and the display 116 to a higher power, in anticipation ofauthenticating the user, and in the case of the display 116, indicatingto the user that the UE 102 is “waking up” and therefore is increasinglyresponsive. As an additional step, the state manager 112 can wait untilthe movement manager 110 determines that the user has moved, picked up,lifted, and so forth the UE 102 before fully powering on theauthentication components, here the infrared sensors. While notrequired, the state manager 112 may cause the authentication to beattempted by the components without further input from the user, therebymaking authentication seamless for the user 120.

In some cases, however, the state manager 112 determines to increasepower or otherwise prepare the state of the UE 102 responsive to bothinertial data and radar data, e.g., the radar manager 106 determiningthat the user is intending to engage and the movement manager 110determining that the user is picking up the UE 102.

Thus, the state manager 112 can wait until a higher level of confidencethat the user's intent is to engage by picking up the UE 102, such as anindication by the movement manager 110 that the user has just started totouch the UE 102. In such a case, the state manager 112 may increasepower based on just the radar manager 106's determination but may do soto an intermediate-power level of a display or the authentication system114 or component thereof, instead waiting until the movement manager 110indicates a touch by the user to fully power these components. As noted,however, the state manager 112 may alter states to higher power levelssolely on determination of an intent to engage based on radar data orlower those levels solely on determination of an intent do disengagebased on radar data.

One of many example ways in which the state manager 112 can managestates (e.g., to maintain an authenticated state) of the UE 102 is shownin FIG. 1 at example environments 100-1, 100-2, and 100-3.

In the environment 100-1, assume that the user 120, while theirsmartphone is in an authenticated state 122, sits down at a desk, andplaces their smartphone down on desk. They then, as shown in 100-2, sitback to read a book. Conventional techniques often start a timer, anexample of which is shown at 124, and then, after the timer 124 expireswithout any obvious input from the user, de-authenticates and otherwisealters the states of the device. If, as is common, the time period isfive minutes, the UE 102 de-authenticates (e.g., “locks”) after fiveminutes. If the user 120 wishes to access the UE 102, they mustre-authenticate. This provides a poor user experience and wastes power,often resulting in reduced battery life, further reducing the user'sexperience with their user equipment.

In contrast to the conventional techniques, on expiration of the timer124, as is shown at 100-3, the UE 102 remains in the authenticated state122. To maintain the authenticated state 122, the radar system 104provides the radar field 118, from which radar data is receivedindicating that the user 120 is either present (which is the case,within arm's reach) or that the user 120 is otherwise passively engaged(such as holding or looking toward the UE 102, which is not the case).The radar manager 106 determines, based on this radar data, that theuser 120 is within arm's reach in this case. The radar manager 106passes this determination to the state manager 112, which in turnsmaintains the authenticated state 122 even though a potentialdisengagement (the timer 124 expiring) was previously determined.

This is but one example of how the techniques and systems enable aseamless user experience for users, which can not only save users timebut power and battery life as well.

Note that in this example the authenticated state 122 is maintained bythe state manager 112, and that the power and information states are notshown to be reduced. The power and information states can be maintainedor reduced, examples of which are described in detail below.

Furthermore, in this example the potential disengagement is determinedby the state manager 112 based on the timer 124 expiring. Anotherpotential disengagement can instead (or also) be determined based on theplacing of the UE 102 on the table. This placing results in the IMU 108sensing, and then providing inertial data, to the movement manager 110.The movement manager 110 determines, based on this inertial data, thatthe UE 102 has moved. At this point the movement manager 110 may passthis movement determination to the radar manager 106 (to determinepassive engagement) or the state manager 112. After the timer 124expiring or the movement data indicating movement, the radar manager 106determines that the user is passively engaged, as noted above.

Not only can the state manager 112 maintain an authenticated state, thestate manager 112 may increase or decrease states of the UE 102. By wayof a detailed example of increasing a power state, consider theauthentication system 114, shown in FIG. 2. This is but one example, asother authentication systems controllable by the state manager 112 areconsidered, such as password-entry through a touch-sensitive display,radar authentication using the radar system 104, or a finger-printreader, to name just a few.

This example of the authentication system 114 is illustrated showing aninterior 200 of the UE 102 (shown as a smartphone). In the depictedconfiguration, the UE 102 includes a radar integrated circuit 202 of theradar system 104, a speaker 204, a front-facing camera 206, a proximitysensor 208, and an ambient light sensor 210. The UE 102 also includes aface-unlock sensor 212, which includes a near-infrared (NIR) floodilluminator 214 and a near-infrared (NIR) dot projector 216, both ofwhich project infrared or near-infrared light on a user. The face-unlocksensor 212 also includes two NIR cameras 218-1 and 218-2, which arepositioned on opposite sides of the UE 102. The NIR cameras 218-1 and218-2 sense the infrared and near-infrared light that is reflected bythe user. This reflected near-infrared light can be used to determinefacial features and, with these features, determine if the user isauthentic based on comparison with previously-stored facial-featureinformation. The NIR flood illuminator 214, for example, “floods” anenvironment with NIR light, which provides, on receiving the reflectionfrom the user (and other objects), an image. This image includes, evenin low or no ambient light, the face of a user, and thus can be used todetermine facial features. The NIR dot projector 216 provides NIR lightreflections that can be analyzed to determine depth of objects,including features of a user's face. Thus, a depth map (e.g., a spectrumdepth map) for the user can be created (e.g., previously when setting upfacial authentication) and a current depth map can be determined andcompared to the stored, previously-created depth map. This depth mapaids in preventing authentication of a picture or other two-dimensionalrendering of a user's face (rather than the person's actual face).

This mapping of a user's facial features can be stored securely on theUE 102 and, based on a user's preferences, be both secure on the UE 102and prevented from being made available to external entities.

The authentication system 114 includes the face-unlock sensor 212, butcan also include other components, such as the front-facing camera 206,the proximity sensor 208 and the ambient light sensor 210, as well asprocessors to analyze the data, memory (which may have multiple powerstates as well) to store, cache, or buffer the sensor data, and soforth.

The face-unlock sensor 212 senses IR (infrared) and NIR (near-infrared)data to perform facial recognition, which is one way in which thetechniques may authenticate the user and therefore alter an access state(e.g., to unlock the UE 102) as noted in the methods described below. Toconserve power, the face-unlock sensor 212 operates in a low-power state(which can also be simply off) when not in use. In particular, the NIRflood illuminator 214 and the NIR dot projector 216 do not radiate inthe off-state. However, a warm-up sequence associated with transitioningfrom a low or no-power state to an intermediate-power state and/or ahigh-power state can be used for the NIR flood illuminator 214 and theNIR dot projector 216. By increasing a power level of one or both ofthese components, the latency in authenticating the user can be reduced,sometimes by a half-second or more. Given the tens or even hundreds oftimes many users authenticate their devices each day, this can save theusers time and improve their experience. As noted herein, this timedelay is reduced by the radar manager 106 determining that the user isintending to engage with their device based on radar data provided bythe radar system 104. This is managed by the state manager 112. Ineffect, the techniques proactively detect the user's intent to engageand initiate the warm-up sequence. The techniques may do so even priorto the user touching the UE 102, though this is not required. Thus, thetechniques enable the NIR flood illuminator 214 and the NIR dotprojector 216 to be sufficiently powered to be used in authenticatingthe user, which reduces time spent by the user waiting for facialrecognition to complete.

Before moving on to other components in the UE 102, consider an aspectof the face-unlock sensor 212. This example component of theauthentication system 114 can authenticate a user using facialrecognition in as little as ten degrees relative to the plane of thedisplay 116. Thus, the user need not pick up the phone and turn thesensors to their face, such as at an angle of 70 to 110 or 80 to 100degrees, instead, the authentication system 114, using the face-unlocksensor 212, is configured to authenticate the user before they even pickup the UE 102. This is illustrated in FIG. 3, which shows the user 120,with portions of their face that are used in facial recognition (e.g.,their chin, nose, or cheekbones) at an angle 302, which can be as littleas ten degrees relative to plane 304 of the display 116. Also shown, theuser 120 is authenticated while having their face more than one meteraway from the face-unlock sensor 212, shown at facial distance 306. Byso doing, the techniques permit nearly seamless and immediateauthentication, even with the UE 102 oriented upside-down or at oddangles.

In more detail, consider FIG. 4, which illustrates an exampleimplementation 400 of the UE 102 (including the radar manager 106, themovement manager 110, and the state manager 112) that can implementtechniques for maintaining an authenticated state and other techniques.The UE 102 of FIG. 4 is illustrated with a variety of example devices,including a UE 102-1, a tablet 102-2, a laptop 102-3, a desktop computer102-4, a computing watch 102-5, computing spectacles 102-6, a gamingsystem 102-7, a home-automation and control system 102-8, and amicrowave 102-9. The UE 102 can also include other devices, such astelevisions, entertainment systems, audio systems, automobiles, drones,track pads, drawing pads, netbooks, e-readers, home security systems,and other home appliances. Note that the UE 102 can be wearable,non-wearable but mobile, or relatively immobile (e.g., desktops andappliances).

Exemplary overall lateral dimensions of the UE 102 can be, for example,approximately eight centimeters by approximately fifteen centimeters.Exemplary footprints of the radar system 104 can be even more limited,such as approximately four millimeters by six millimeters with antennasincluded. The requirement of such a limited footprint for the radarsystem 104, which is needed to accommodate the many other desirablefeatures of the UE 102 in such a space-limited package combined withpower and processing limitations, can lead to compromises in theaccuracy and efficacy of radar gesture detection, at least some of whichcan be overcome in view of the teachings herein.

The UE 102 also includes one or more computer processors 402 and one ormore computer-readable media 404, which includes memory media andstorage media. Applications and/or an operating system (not shown)implemented as computer-readable instructions on the computer-readablemedia 404 can be executed by the computer processors 402 to provide someor all of the functionalities described herein, such as some or all ofthe functions of the radar manager 106, the movement manager 110, andthe state manager 112 (shown within the computer-readable media 404,though this is not required).

The UE 102 may also include a network interface 406. The UE 102 can usethe network interface 406 for communicating data over wired, wireless,or optical networks. By way of example and not limitation, the networkinterface 406 may communicate data over a local-area-network (LAN), awireless local-area-network (WLAN), a personal-area-network (PAN), awide-area-network (WAN), an intranet, the Internet, a peer-to-peernetwork, point-to-point network, or a mesh network.

In aspects, the radar system 104 is implemented at least partially inhardware. Various implementations of the radar system 104 can include aSystem-on-Chip (SoC), one or more Integrated Circuits (ICs), a processorwith embedded processor instructions or configured to access processorinstructions stored in memory, hardware with embedded firmware, aprinted circuit board with various hardware components, or anycombination thereof The radar system 104 operates as a monostatic radarby transmitting and receiving its own radar signals. In someimplementations, the radar system 104 may also cooperate with otherradar systems 104 that are within an external environment to implement abistatic radar, a multistatic radar, or a network radar. Constraints orlimitations of the UE 102, however, may impact a design of the radarsystem 104. The UE 102, for example, may have limited power available tooperate the radar, limited computational capability, size constraints,layout restrictions, an exterior housing that attenuates or distortsradar signals, and so forth. The radar system 104 includes severalfeatures that enable advanced radar functionality and high performanceto be realized in the presence of these constraints, as furtherdescribed below.

Prior to setting out additional example ways in which the state manager112 may act, consider FIG. 5, which illustrates the many information,power, and access states in which the UE 102 may operate and which canbe managed by the state manager 112.

FIG. 5 illustrates access, information, and power states in which the UE102 may operate, each of which can be managed by the describedtechniques. These example levels and types of device states 500 areshown in three levels of granularity for visual brevity, though manylevels of each are contemplated for access state 502, power state 504,and information state 506. The access state 502 is shown with threeexamples levels of granularity, high-access state 502-1,intermediate-access state 502-2, and low-access state 502-3. Similarly,the power state 504 is shown three examples levels of granularity,high-power state 504-1, intermediate-power state 504-2, and low-powerstate 504-3. Likewise, the information state 506 is shown three exampleslevels of granularity, high-information state 506-1,intermediate-information state 506-2, and low-information state 506-3.

In more detail, the access state 502 is concerned with the access rightsavailable to a user of the device to the data, applications, functions,accounts, or components of the UE 102. This access can be high,sometimes referred to as an “unlocked” state for the UE 102. Thishigh-access level can include simply the applications and functions ofthe device, or may also include access to various accounts, such as bankaccounts, social-media accounts, and so forth that are accessiblethrough the UE 102. Many computing devices, such as the UE 102, requireauthentication to provide high access, such as the high-access state502-1.

Various intermediate levels of access (e.g., 502-2) can be permittedwith or without authentication by the UE 102 (e.g., depending on a userpreference or an operating system default setting). Thisintermediate-access state 502-2 permits a user to access some but notall accounts, services, or components of the UE 102. Examples includeallowing a user to take pictures but not to access previously-capturedpictures. Other examples include allowing the user to answer a telephonecall but not access a contact list when making a telephone call. Theseare but a few of the many intermediate rights that the UE 102 canpermit, shown with the intermediate-access state 502-2.

The authenticated state 122, as noted above, is concerned with accesspermitted by the UE 102. Thus, a user is authenticated and then accessis granted. As noted throughout this document, the techniques andsystems described enable greater security, where access to the UE 102 isboth easier for a user and more likely that the access granted is to theauthenticated user rather than a third party. This authentication state122 can permit a high or intermediate level of access, such as thehigh-access state 502-1 or the intermediate-access state 502-2, as notedabove, and illustrated in FIG. 5 with a dashed-line box including thehigh-access state 502-1 and the intermediate-access state 502-2.

Lastly, the access state 502 can refrain from permitting access, shownas the low-access state 502-3. In this case the device may be on, sendnotifications like an alarm to wake up a user, and so forth, but notpermit access to functions of the UE 102 (or the UE 102 may simply beoff, and thus permit no access).

The power state 504 is shown with three examples levels of granularity,the high-power state 504-1, the intermediate-power state 504-2, and thelow-power state 504-3. The power state 504 is concerned with an amountof power to one or more components of the UE 102, such as the radarsystem 104, the display 116, or other power-consuming components, suchas processors, cameras, microphone, voice assistant, touchscreen,sensors, radar, and components that are part of the authenticationsystem 114 (which may include the previous components listed as well).In the context of powering up a component, as well as the power states504 generally, the terms power, powering up, increasing power, reducingpower, and so forth can include, control of a power-managementintegrated circuit (PMIC); managing power rails extending from the PMIC;opening and closing switches between a power rail, the PMIC, and one ormore circuit components (e.g., the mentioned NIR components, cameras,displays, and radar); and providing a supply voltage to accurately andsafely operate a component, which may include ramping or distributing anapplied voltage or managing current in-rush.

Regarding the radar system 104, the power state 504 can be reduced bycollecting radar data at different duty cycles (e.g., lower frequenciesmay use less power and higher frequencies may use more power), turningvarious components off when the components are not active, or adjustinga power amplification level. By so doing, the radar system 104 may useapproximately 90 mW of power at the high-power state 504-1, 30 to 60 mWat the intermediate-power state 504-2, or less than 30 mW at thelow-power state 504-3 (e.g., the radar system 104 can operate from 2 to20 mW while still providing some usable radar data, such as userpresence). Each of these levels of power usage permit differentresolutions and distance. Additional details regarding power managementof the radar system 104 (and the UE 102) are described with reference toFIG. 6-1.

In the context of altering states noted above, the state manager 112,based on the determinations by the radar manager 106 and the movementmanager 110, may increase or decrease power to various components of theUE 102.

For example, the state manager 112 can alter the power of theauthentication system 114 or the display 116 from a lower-power state(e.g., the low-power state 504-3 to the intermediate-power state 504-2or either of these to the high-power state 504-1). By so doing, the UE102 may more-quickly or more-easily engage with a user or authenticatethe user. Thus, the state manager 112 may alter the power-state 504 tobe a higher or lower power than is currently the case for that system ofthe UE 102 or for particular power-consuming entities associated withthe UE 102. Example components are described further as part of FIG. 2above, including powering up or down the face-unlock sensor 212 and itscomponents, the NIR flood illuminator 214 and the NIR dot projector 216,as well as the NIR cameras 218-1 and 218-2, reducing power to thesecomponents, a display, microphone, touch-input sensor, and so forth.

The third example state of the UE 102 is the information state 506,which is illustrated with the high-information state 506-1, theintermediate-information state 506-2, and the low-information state506-3. In more detail, the information state 506 is concerned with anamount of information provided to a user, e.g., the user 120 of FIG. 1.In the context of notifications, the high-information state 506-1provides a highest level of information, and generally assumes that theUE 102 is unlocked or otherwise authenticated, or has a user preferencefor providing high levels of information even without authentication.Examples include, for the high-information state 506-1, showing acaller's name, number, and even associated image when a call isreceived. Similarly, when a text or email is received, or other type ofmessage, the content is automatically presented through the display 116or audio speakers, a peripheral, and so forth. This assumes a high-levelof engagement, though a user's preferences can determine what engagementis required. Here it is assumed that there is some correlation betweenthe user's engagement and the amount of information provided, andtherefore, the techniques, by determining engagement, can tailor theinformation presented to that determination. Examples of reducedinformation, e.g., the intermediate-information state 506-2, includepresenting a ring tone when a call is received but not the caller'sname/identification, indicating that text message or email has beenreceived but only the subject line, or only the address, or part of thecontent in the body but not all of it, and so forth. The low-informationstate 506-3 presents little to no information that is personallyassociated with the user 120, but can include information that isgeneric or widely considered common knowledge or non-sensitive, such asthe display 116 showing a current date, time, weather condition,battery-power status, or that the UE 102 is on. Other examples of thelow-information state 506-3 include a blank or black screen when a textmessage is received with an audible “ping” indicating only that amessage has been received, or a ring tone for a call, but not the name,number, or other information about the caller.

FIG. 6-1 illustrates an example implementation 600 of the radar system104. In the example 600, the radar system 104 includes at least one ofeach of the following components: a communication interface 602, anantenna array 604, a transceiver 606, a processor 608, and a systemmedia 610 (e.g., one or more computer-readable storage media). Theprocessor 608 can be implemented as a digital signal processor, acontroller, an application processor, another processor (e.g., thecomputer processors 402 of the UE 102) or some combination thereof. Thesystem media 610, which may be included within, or be separate from, thecomputer-readable media 404 of the UE 102, includes one or more of thefollowing modules: an attenuation mitigator 614, a digital beamformer616, an angle estimator 618, or a power-management module 620. Thesemodules can compensate for, or mitigate the effects of, integrating theradar system 104 within the UE 102, thereby enabling the radar system104 to recognize small or complex gestures, distinguish betweendifferent orientations of the user (e.g., “reach”), continuously monitoran external environment, or realize a target false-alarm rate. Withthese features, the radar system 104 can be implemented within a varietyof different devices, such as the devices illustrated in FIG. 4.

Using the communication interface 602, the radar system 104 can provideradar data to the radar manager 106. The communication interface 602 maybe a wireless or wired interface based on the radar system 104 beingimplemented separate from, or integrated within, the UE 102. Dependingon the application, the radar data may include raw or minimallyprocessed data, in-phase and quadrature (I/Q) data, range-Doppler data,processed data including target location information (e.g., range,azimuth, elevation), clutter map data, and so forth. Generally, theradar data contains information that is usable by the radar manager 106for providing a user's intent to engage, disengage, or maintainengagement to the state manager 112.

The antenna array 604 includes at least one transmitting antenna element(not shown) and at least two receiving antenna elements (as shown inFIG. 7). In some cases, the antenna array 604 may include multipletransmitting antenna elements to implement a multiple-inputmultiple-output (MIMO) radar capable of transmitting multiple distinctwaveforms at a time (e.g., a different waveform per transmitting antennaelement). The use of multiple waveforms can increase a measurementaccuracy of the radar system 104. The receiving antenna elements can bepositioned in a one-dimensional shape (e.g., a line) or atwo-dimensional shape for implementations that include three or morereceiving antenna elements. The one-dimensional shape enables the radarsystem 104 to measure one angular dimension (e.g., an azimuth or anelevation) while the two-dimensional shape enables two angulardimensions to be measured (e.g., both azimuth and elevation). Exampletwo-dimensional arrangements of the receiving antenna elements arefurther described with respect to FIG. 7.

FIG. 6-2 illustrates an example transceiver 606 and processor 608. Thetransceiver 606 includes multiple components that can be individuallyturned on or off via the power-management module 620 in accordance withan operational state of the radar system 104. Note that thepower-management module 620 can be separate, integrated with, or underthe control of the state manager 112, such as in cases where the statemanager 112 is powering up or down components (e.g., the authenticationsystem 114) used to authenticate a user. The transceiver 606 is shown toinclude at least one of each of the following components: an activecomponent 622, a voltage-controlled oscillator (VCO) andvoltage-controlled buffer 624, a multiplexer 626, an analog-to-digitalconverter (ADC) 628, a phase lock loop (PLL) 630, and a crystaloscillator 632. If turned on, each of these components consume power,even if the radar system 104 is not actively using these components totransmit or receive radar signals. The active component 622, forexample, can include an amplifier or filter that is coupled to a supplyvoltage. The VCO 624 generates a frequency-modulated radar signal basedon a control voltage that is provided by the PLL 630. The crystaloscillator 632 generates a reference signal for signal generation,frequency conversion (e.g., upconversion or downconversion), or timingoperations within the radar system 104. By turning these components onor off, the power-management module 620 enables the radar system 104 toquickly switch between active and inactive operational states andconserve power during various inactive time periods. These inactive timeperiods may be on the order of microseconds (μs), milliseconds (ms), orseconds (s).

The processor 608 is shown to include multiple processors that consumedifferent amounts of power, such as a low-power processor 608-1 and ahigh-power processor 608-2. As an example, the low-power processor 608-1can include a processor that is embedded within the radar system 104 andthe high-power processor can include the computer processors 402 or someother processor that is external to the radar system 104. Thedifferences in power consumption can result from different amounts ofavailable memory or computational ability. For instance, the low-powerprocessor 608-1 may utilize less memory, perform fewer computations, orutilize simpler algorithms relative to the high-power processor 608-2.Despite these limitations, the low-power processor 608-1 can processdata for less-complex radar-based applications, such as proximitydetection or motion detection (based on radar data rather than inertialdata). The high-power processor 608-2, in contrast, may utilize a largeamount of memory, perform a large amount of computations, or executecomplex signal processing, tracking, or machine-learning algorithms. Thehigh-power processor 608-2 may process data for high-profile radar-basedapplications, such as gesture recognition, facial recognition (for theauthentication system 114), and provide accurate, high-resolution datathrough the resolution of angular ambiguities or distinguishing ofmultiple users and features thereof.

To conserve power, the power-management module 620 can control whetherthe low-power processor 608-1 or the high-power processor 608-2 are usedto process the radar data. In some cases, the low-power processor 608-1can perform a portion of the analysis and pass data onto the high-powerprocessor 608-2. Example data may include a clutter map, raw orminimally processed radar data (e.g., in-phase and quadrature data orrange-Doppler data), or digital beamforming data. The low-powerprocessor 608-1 may also perform some low-level analysis to determinewhether there is anything of interest in the environment for thehigh-power processor 608-2 to analyze. In this way, power can beconserved by limiting operation of the high-power processor 608-2 whileutilizing the high-power processor 608-2 for situations in whichhigh-fidelity or accurate radar data is requested by the radar-basedapplication. Other factors that can impact power consumption within theradar system 104 are further described with respect to FIG. 6-1.

These and other capabilities and configurations, as well as ways inwhich entities of FIGS. 1, 2, 4, and 6-9 act and interact, are set forthin greater detail below. These entities may be further divided,combined, and so on. The environment 100 of FIG. 1 and the detailedillustrations of FIG. 2 through FIG. 9 illustrate some of many possibleenvironments and devices capable of employing the described techniques.FIGS. 6-9 describe additional details and features of the radar system104. In FIGS. 6-9, the radar system 104 is described in the context ofthe UE 102, but as noted above, the applicability of the features andadvantages of the described systems and techniques are not necessarilyso limited, and other embodiments involving other types of electronicdevices may also be within the scope of the present teachings.

FIG. 7 illustrates example arrangements 700 of receiving antennaelements 702. If the antenna array 604 includes at least four receivingantenna elements 702, for example, the receiving antenna elements 702can be arranged in a rectangular arrangement 704-1 as depicted in themiddle of FIG. 7. Alternatively, a triangular arrangement 704-2 or anL-shape arrangement 704-3 may be used if the antenna array 604 includesat least three receiving antenna elements 702.

Due to a size or layout constraint of the UE 102, an element spacingbetween the receiving antenna elements 702 or a quantity of thereceiving antenna elements 702 may not be ideal for the angles at whichthe radar system 104 is to monitor. In particular, the element spacingmay cause angular ambiguities to be present that make it challenging forconventional radars to estimate an angular position of a target.Conventional radars may therefore limit a field of view (e.g., anglesthat are to be monitored) to avoid an ambiguous zone, which has theangular ambiguities, and thereby reduce false detections. For example,conventional radars may limit the field of view to angles betweenapproximately −45 degrees to 45 degrees to avoid angular ambiguitiesthat occur using a wavelength of 8 millimeters (mm) and an elementspacing of 6.5 mm (e.g., the element spacing being 90% of thewavelength). Consequently, the conventional radar may be unable todetect targets that are beyond the 45-degree limits of the field ofview. In contrast, the radar system 104 includes the digital beamformer616 and the angle estimator 618, which resolve the angular ambiguitiesand enable the radar system 104 to monitor angles beyond the 45-degreelimit, such as angles between approximately −90 degrees to 90 degrees,or up to approximately −180 degrees and 180 degrees. These angularranges can be applied across one or more directions (e g., azimuthand/or elevation). Accordingly, the radar system 104 can realize lowfalse-alarm rates for a variety of different antenna array designs,including element spacings that are less than, greater than, or equal tohalf a center wavelength of the radar signal.

Using the antenna array 604, the radar system 104 can form beams thatare steered or un-steered, wide or narrow, or shaped (e.g., as ahemisphere, cube, fan, cone, or cylinder). As an example, the one ormore transmitting antenna elements (not shown) may have an un-steeredomnidirectional radiation pattern or may be able to produce a wide beam,such as the wide transmit beam 706. Either of these techniques enablethe radar system 104 to illuminate a large volume of space. To achievetarget angular accuracies and angular resolutions, however, thereceiving antenna elements 702 and the digital beamformer 616 can beused to generate thousands of narrow and steered beams (e.g., 3000beams, 7000 beams, or 9000 beams), such as the narrow receive beam 708.In this way, the radar system 104 can efficiently monitor the externalenvironment and accurately determine arrival angles of reflectionswithin the external environment.

Returning to FIG. 6-1, the transceiver 606 includes circuitry and logicfor transmitting and receiving radar signals via the antenna array 604.Components of the transceiver 606 can include amplifiers, mixers,switches, analog-to-digital converters, filters, and so forth forconditioning the radar signals. The transceiver 606 can also includelogic to perform in-phase/quadrature (I/Q) operations, such asmodulation or demodulation. The transceiver 606 can be configured forcontinuous wave radar operations or pulsed radar operations. A varietyof modulations can be used to produce the radar signals, includinglinear frequency modulations, triangular frequency modulations, steppedfrequency modulations, or phase modulations.

The transceiver 606 can generate radar signals within a range offrequencies (e.g., a frequency spectrum), such as between 1 gigahertz(GHz) and 400 GHz, between 4 GHz and 100 GHz, or between 57 GHz and 63GHz. The frequency spectrum can be divided into multiple sub-spectrathat have a similar bandwidth or different bandwidths. The bandwidthscan be on the order of 500 megahertz (MHz), 1 GHz, 2 GHz, and so forth.As an example, different frequency sub-spectra may include frequenciesbetween approximately 57 GHz and 59 GHz, 59 GHz and 61 GHz, or 61 GHzand 63 GHz. Multiple frequency sub-spectra that have a same bandwidthand may be contiguous or non-contiguous may also be chosen forcoherence. The multiple frequency sub-spectra can be transmittedsimultaneously or separated in time using a single radar signal ormultiple radar signals. The contiguous frequency sub-spectra enable theradar signal to have a wider bandwidth while the non-contiguousfrequency sub-spectra can further emphasize amplitude and phasedifferences that enable the angle estimator 618 to resolve angularambiguities. The attenuation mitigator 614 or the angle estimator 618may cause the transceiver 606 to utilize one or more frequencysub-spectra to improve performance of the radar system 104, as furtherdescribed with respect to FIGS. 8 and 9. Some embodiments of thetechniques are particularly advantageous, such as when the UE 102 is ahandheld smartphone, the radar signals are in the 57 Ghz-64 Ghz band, apeak effective isotropic radiated power (EIRP) is in the range of 10dBm-20 dBm (10 mW-100 mW), and an average power-spectral density isabout 13 dBm/MHz, which has been found to suitably address radiationhealth and co-existence issues while also providing a nicely-sized“bubble” of radar detection (e.g., at least one meter and often up to orexceeding two meters in extent) near-around the smartphone and the userwithin which the described methods for authentication management throughIMU and radar provided particularly good time-saving convenience whileconserving power.

A power-management module 620 manages power usage to balance performanceand power consumption. For example, the power-management module 620communicates with the radar manager 106 to cause the radar system 104 tocollect data using a predefined radar-power state. Each predefinedradar-power state can be associated with a particular framing structure,a particular transmit power level, or particular hardware (e.g., thelow-power processor 608-1 or the high-power processor 608-2 of FIG.6-2). Adjusting one or more of these affects the radar system's 104power consumption. Reducing power consumption, however, affectsperformance, such as a gesture-frame update rate and response delay,which are described below.

FIG. 6-3 illustrates an example relationship between power consumption,a gesture-frame update rate 634, and a response delay. In graph 636,radar-power states 638-1, 638-2, and 638-3 are associated with differentlevels of power consumption and different gesture-frame update rates634. The gesture-frame update rate 634 represents how often the radarsystem 104 actively monitors the external environment by transmittingand receiving one or more radar signals. Generally speaking, the powerconsumption is proportional to the gesture-frame update rate 634. Assuch, higher gesture-frame update rates 634 result in larger amounts ofpower being consumed by the radar system 104.

In graph 636, the radar-power state 638-1 utilizes a smallest amount ofpower whereas the radar-power state 638-3 consumes a largest amount ofpower. As an example, the radar-power state 638-1 consumes power on theorder of a few milliwatts (mW) (e.g., between approximately 2 mW and 4mW) whereas the radar-power state 638-3 consumes power on the order ofseveral milliwatts (e.g., between approximately 6 mW and 20 mW). Interms of the gesture-frame update rate 634, the radar-power state 638-1uses an update rate that is on the order of a few hertz (e.g.,approximately 1 Hz or less than 5 Hz) while the radar-power state 638-3uses a gesture-frame update rate 634 that is on the order of tens ofhertz (e.g., approximately 20 Hz or greater than 10 Hz).

Graph 640 depicts a relationship between the response delay and thegesture-frame update rate 634 for the different radar-power states 638-1to 638-3. Generally speaking, the response delay isinversely-proportional to both the gesture-frame update rate 634 and thepower consumption. In particular, the response delay exponentiallydecreases while the gesture-frame update rate 634 increases. Theresponse delay associated with the radar-power state 638-1 may be on theorder of hundreds of milliseconds (ms) (e.g., 1000 ms or more than 200ms) while the response delay associated with the radar-power state 638-3may be on the order of several milliseconds (e.g., 50 ms or less than100 ms). For the radar-power state 638-2, the power consumption,gesture-frame update rate 634, and response delay are between that ofthe radar-power state 638-1 and the radar-power state 638-3. Forinstance, the radar-power state's 638-2 power consumption isapproximately 5 mW, the gesture-frame update rate is approximately 8 Hz,and the response delay is between approximately 100 ms and 200 ms.

Instead of operating at either the radar-power state 638-1 or theradar-power state 638-3, the power-management module 620 dynamicallyswitches between the radar-power states 638-1, 638-2, and 638-3 (andsub-states between each of these radar-power states 638) such that theresponse delay and the power consumption are managed together based onthe activity within the environment. As an example, the power-managementmodule 620 activates the radar-power state 638-1 to monitor the externalenvironment or detect an approaching user. Later in time, thepower-management module 620 activates the radar-power state 638-3 if theradar system 104 determines the user is showing an intent to engage ormay be starting to do so, or starting to perform a gesture. Differenttriggers may cause the power-management module 620 to switch between thedifferent radar-power states 638-1 through 638-3. Example triggersinclude motion or the lack of motion, appearance or disappearance of theuser, the user moving into or out of a designated region (e.g., a regiondefined by range, azimuth, or elevation), a change in velocity of amotion associated with the user, an intent to engage determined by theradar manager 106 (e.g., a “reach” though some intents to engage requireadditional power, such as facial feature tracking), or a change inreflected signal strength (e.g., due to changes in radar cross section).In general, the triggers that indicate a lower probability of the userinteracting with the UE 102 or a preference to collect data using alonger response delay may cause the radar-power state 638-1 to beactivated to conserve power.

In general, the power-management module 620 determines when and howpower can be conserved, and incrementally adjusts power consumption toenable the radar system 104 to operate within power limitations of theUE 102. In some cases, the power-management module 620 may monitor anamount of available power remaining and adjust operations of the radarsystem 104 accordingly (e.g., due to a low battery). For example, if theremaining amount of power is low, the power-management module 620 maycontinue operating in the radar-power state 638-1 instead of switchingto either of the radar-power states 638-2 or 638-3.

Each power state 638-1 to 638-3 can be associated with a particularframing structure. The framing structure specifies a configuration,scheduling, and signal characteristics associated with the transmissionand reception of the radar signals. In general, the framing structure isset up such that the appropriate radar data can be collected based onthe external environment. The framing structure can be customized tofacilitate collection of different types of radar data for differentapplications (e.g., proximity detection, feature recognition, or gesturerecognition). During inactive times throughout each level of the framingstructure, the power-management module 620 can turn off the componentswithin the transceiver 606 in FIG. 6-2 to conserve power. An exampleframing structure is further described with respect to FIG. 6-4.

FIG. 6-4 illustrates an example framing structure 642. In the depictedconfiguration, the framing structure 642 includes three different typesof frames. At a top level, the framing structure 642 includes a sequenceof gesture frames 644, which can be in the active state or the inactivestate. Generally speaking, the active state consumes a larger amount ofpower relative to the inactive state. At an intermediate level, theframing structure 642 includes a sequence of feature frames (FF) 646,which can similarly be in the active state or the inactive state.Different types of feature frames include a pulse-mode feature frame 648(shown at the bottom-left of FIG. 6-4) and a burst-mode feature frame650 (shown at the bottom-right of FIG. 6-4). At a low level, the framingstructure 642 includes a sequence of radar frames (RF) 652, which canalso be in the active state or the inactive state.

The radar system 104 transmits and receives a radar signal during anactive radar frame (RF) 652. In some situations, the radar frames 652are individually analyzed for basic radar operations, such as search andtrack, clutter-map generation, user location determination, and soforth. Radar data collected during each active radar frame 652 can besaved to a buffer after completion of the radar frame 652 or provideddirectly to the processor 608 of FIG. 6-1.

100801 The radar system 104 analyzes the radar data across multipleradar frames 652 (e.g., across a group of radar frames 652 associatedwith an active feature frame 646) to identify a particular featureassociated with one or more gestures. Example types of features includea particular type of motion, a motion associated with a particularappendage (e.g., a hand or individual fingers), and a feature associatedwith different portions of the gesture. To recognize a gesture performedby the user 120 during an active gesture frame 644, the radar system 104analyzes the radar data associated with one or more active featureframes 646.

Depending upon the type of gesture, a duration of the gesture frame 644may be on the order of milliseconds or seconds (e.g., betweenapproximately 10 ms and 10 s). After the active gesture frames 644occur, the radar system 104 is inactive, as shown by inactive gestureframes 644-3 and 644-4. A duration of the inactive gesture frames 644 ischaracterized by a deep sleep time 654, which may be on the order oftens of milliseconds or more (e.g., greater than 50 ms). In an exampleimplementation, the radar system 104 can turn off all of the componentswithin the transceiver 606 to conserve power during the deep sleep time654.

In the depicted framing structure 642, each gesture frame 644 includes Kfeature frames 646, where K is a positive integer. If the gesture frame644 is in the inactive state, all of the feature frames 646 associatedwith that gesture frame 644 are also in the inactive state. In contrast,an active gesture frame 644 includes J active feature frames 646 and K-Jinactive feature frames 646, where J is a positive integer that is lessthan or equal to K. A quantity of feature frames 646 can be based on acomplexity of the gesture and may include a few to a hundred featureframes 646 (e.g., K may equal 2, 10, 30, 60, or 100). A duration of eachfeature frame 646 may be on the order of milliseconds (e.g., betweenapproximately 1 ms and 50 ms).

To conserve power, the active feature frames 646-1 to 646-J occur priorto the inactive feature frames 646-(J+1) to 646-K. A duration of theinactive feature frames 646-(J+1) to 646-K is characterized by a sleeptime 656. In this way, the inactive feature frames 646-(J+1) to 646-Kare consecutively executed such that the radar system 104 can be in apowered-down state for a longer duration relative to other techniquesthat interleave the inactive feature frames 646-(J+1) to 646-K with theactive feature frames 646-1 to 646-J. Generally speaking, increasing aduration of the sleep time 656 enables the radar system 104 to turn offcomponents within the transceiver 606 that require longer start-uptimes.

Each feature frame 646 includes L radar frames 652, where L is apositive integer that may or may not be equal to J or K. In someimplementations, a quantity of radar frames 652 may vary acrossdifferent feature frames 646 and may comprise a few frames or hundredsof frames (e.g., L may equal 5, 15, 30, 100, or 500). A duration of aradar frame 652 may be on the order of tens or thousands of microseconds(e.g., between approximately 30 μs and 5 ms). The radar frames 652within a particular feature frame 646 can be customized for apredetermined detection range, range resolution, or Doppler sensitivity,which facilitates detection of a particular feature and gesture. Forexample, the radar frames 652 may utilize a particular type ofmodulation, bandwidth, frequency, transmit power, or timing. If thefeature frame 646 is in the inactive state, all of the radar frames 652associated with that feature frame 646 are also in the inactive state.

The pulse-mode feature frame 648 and the burst-mode feature frame 650include different sequences of radar frames 652. Generally speaking, theradar frames 652 within an active pulse-mode feature frame 648 transmitpulses that are separated in time by a predetermined amount. Incontrast, the radar frames 652 within an active burst-mode feature frame650 transmit pulses continuously across a portion of the burst-modefeature frame 650 (e.g., the pulses are not separated by a predeterminedamount of time).

Within each active pulse-mode feature frame 648, the sequence of radarframes 652 alternates between the active state and the inactive state.Each active radar frame 652 transmits a radar signal (e.g., chirp),which is illustrated by a triangle. A duration of the radar signal ischaracterized by an active time 658. During the active time 658, thecomponents within the transceiver 606 are powered-on. During ashort-idle time 660, which includes the remaining time within the activeradar frame 652 and a duration of the following inactive radar frame652, the radar system 104 conserves power by turning off componentswithin the transceiver 606 that have a start-up time within a durationof the short-idle time 660.

An active burst-mode feature frame 650 includes M active radar frames652 and L-M inactive radar frames 652, where M is a positive integerthat is less than or equal to L. To conserve power, the active radarframes 652-1 to 652-M occur prior to the inactive radar frames 652-(M+1)to 652-L. A duration of the inactive radar frames 652-(M+1) to 652-L ischaracterized by a long-idle time 662. By grouping the inactive radarframes 652-(M+1) to 652-L together, the radar system 104 can be in apowered-down state for a longer duration relative to the short-idle time660 that occurs during the pulse-mode feature frame 648. Additionally,the power management module 620 can turn off additional componentswithin the transceiver 606 that have start-up times that are longer thanthe short-idle time 660 and shorter that the long-idle time 662.

Each active radar frame 652 within an active burst-mode feature frame650 transmits a portion of a radar signal. In this example, the activeradar frames 652-1 to 652-M alternate between transmitting a portion ofthe radar signal that increases in frequency and a portion of the radarsignal that decreases in frequency.

The framing structure 642 enables power to be conserved throughadjustable duty cycles within each frame type. A first duty cycle 664 isbased on a quantity of active feature frames 646 (J) relative to a totalquantity of feature frames 646 (K). A second duty cycle 665 is based ona quantity of active radar frames 652 (e.g., L/2 or M) relative to atotal quantity of radar frames 652 (L). A third duty cycle 668 is basedon a duration of the radar signal relative to a duration of a radarframe 652.

Consider an example framing structure 642 for the power state 638-1 thatconsumes approximately 2 mW of power and has a gesture-frame update rate634 between approximately 1 Hz and 4 Hz. In this example, the framingstructure 642 includes a gesture frame 644 with a duration betweenapproximately 250 ms and 1 second. The gesture frame 644 includesthirty-one pulse-mode feature frames 648 (e.g., L is equal to 31). Oneof the thirty-one pulse-mode feature frames 648 is in the active state.This results in the duty cycle 664 being approximately equal to 3.2%. Aduration of each pulse-mode feature frame 648 is between approximately 8ms and 32 ms. Each pulse-mode feature frame 648 is composed of eightradar frames 652. Within the active pulse-mode feature frame 648, alleight radar frames 652 are in the active state. This results in the dutycycle 665 being equal to 100%. A duration of each radar frame 652 isbetween approximately 1 ms and 4 ms. An active time 658 within each ofthe active radar frames 652 is between approximately 32 μs and 128 μs.As such, the resulting duty cycle 668 is approximately 3.2%. Thisexample framing structure 642 has been found to yield good performanceresults. These good performance results are in terms of good gesturerecognition and presence detection while also yielding good powerefficiency results in the application context of a handheld smartphonein a low-power state (e.g., low-power state 504-3).

Based on the framing structure 642, the power management module 620 candetermine a time for which the radar system 104 is not activelycollecting radar data. Based on this inactive time period, the powermanagement module 620 can conserve power by adjusting an operationalstate of the radar system 104 and turning off one or more components ofthe transceiver 606, as further described below.

As noted, the power-management module 620 can conserve power by turningoff one or more components within the transceiver 606 (e.g., avoltage-controlled oscillator, a multiplexer, an analog-to-digitalconverter, a phase lock loop, or a crystal oscillator) during inactivetime periods. These inactive time periods occur if the radar system 104is not actively transmitting or receiving radar signals, which may be onthe order of microseconds (μs), milliseconds (ms), or seconds (s).Further, the power-management module 620 can modify transmission powerof the radar signals by adjusting an amount of amplification provided bya signal amplifier. Additionally, the power-management module 620 cancontrol the use of different hardware components within the radar system104 to conserve power. If the processor 608 comprises a lower-powerprocessor and a higher-power processor (e.g., processors with differentamounts of memory and computational capability), for example, thepower-management module 620 can switch between utilizing the lower-powerprocessor for low-level analysis (e.g., detecting motion, determining alocation of a user, or monitoring the environment) and the higher-powerprocessor for situations in which high-fidelity or accurate radar datais requested by the radar manager 106 (e.g., for implementing thehigh-power state 504-1 of the authentication system 114 forauthenticating a user using radar data).

In addition to the internal power-saving techniques described above, thepower-management module 620 can also conserve power within the UE 102 byactivating or deactivating other external components or sensors that arewithin the UE 102, either alone or at a command of the authenticationsystem 114. These external components may include speakers, a camerasensor, a global positioning system, a wireless communicationtransceiver, a display, a gyroscope, or an accelerometer. Because theradar system 104 can monitor the environment using a small amount ofpower, the power-management module 620 can appropriately turn theseexternal components on or off based on where the user is located or whatthe user is doing. In this way, the UE 102 can seamlessly respond to theuser and conserve power without the use of automatic shut-off timers orthe user physically touching or verbally controlling the UE 102.

FIG. 8 illustrates additional details of an example implementation 800of the radar system 104 within the UE 102. In the example 800, theantenna array 604 is positioned underneath an exterior housing of the UE102, such as a glass cover or an external case. Depending on itsmaterial properties, the exterior housing may act as an attenuator 802,which attenuates or distorts radar signals that are transmitted andreceived by the radar system 104. The attenuator 802 may includedifferent types of glass or plastics, some of which may be found withindisplay screens, exterior housings, or other components of the UE 102and have a dielectric constant (e.g., relative permittivity) betweenapproximately four and ten. Accordingly, the attenuator 802 is opaque orsemi-transparent to a radar signal 806 and may cause a portion of atransmitted or received radar signal 806 to be reflected (as shown by areflected portion 804). For conventional radars, the attenuator 802 maydecrease an effective range that can be monitored, prevent small targetsfrom being detected, or reduce overall accuracy.

Assuming a transmit power of the radar system 104 is limited, andre-designing the exterior housing is not desirable, one or moreattenuation-dependent properties of the radar signal 806 (e.g., afrequency sub-spectrum 808 or a steering angle 810) orattenuation-dependent characteristics of the attenuator 802 (e.g., adistance 812 between the attenuator 802 and the radar system 104 or athickness 814 of the attenuator 802) are adjusted to mitigate theeffects of the attenuator 802. Some of these characteristics can be setduring manufacturing or adjusted by the attenuation mitigator 614 duringoperation of the radar system 104. The attenuation mitigator 614, forexample, can cause the transceiver 606 to transmit the radar signal 806using the selected frequency sub-spectrum 808 or the steering angle 810,cause a platform to move the radar system 104 closer or farther from theattenuator 802 to change the distance 812, or prompt the user to applyanother attenuator to increase the thickness 814 of the attenuator 802.

Appropriate adjustments can be made by the attenuation mitigator 614based on pre-determined characteristics of the attenuator 802 (e.g.,characteristics stored in the computer-readable media 404 of the UE 102or within the system media 610) or by processing returns of the radarsignal 806 to measure one or more characteristics of the attenuator 802.Even if some of the attenuation-dependent characteristics are fixed orconstrained, the attenuation mitigator 614 can take these limitationsinto account to balance each parameter and achieve a target radarperformance. As a result, the attenuation mitigator 614 enables theradar system 104 to realize enhanced accuracy and larger effectiveranges for detecting and tracking the user that is located on anopposite side of the attenuator 802. These techniques providealternatives to increasing transmit power, which increases powerconsumption of the radar system 104, or changing material properties ofthe attenuator 802, which can be difficult and expensive once a deviceis in production.

FIG. 9 illustrates an example scheme 900 implemented by the radar system104. Portions of the scheme 900 may be performed by the processor 608,the computer processors 402, or other hardware circuitry. The scheme 900can be customized to support different types of electronic devices andradar-based applications (e.g., the radar manager 106), and also enablesthe radar system 104 to achieve target angular accuracies despite designconstraints.

The transceiver 606 produces raw data 902 based on individual responsesof the receiving antenna elements 702 to a received radar signal. Thereceived radar signal may be associated with one or more frequencysub-spectra 904 that were selected by the angle estimator 618 tofacilitate angular ambiguity resolution. The frequency sub-spectra 904,for example, may be chosen to reduce a quantity of sidelobes or reducean amplitude of the sidelobes (e.g., reduce the amplitude by 0.5 dB, 1dB, or more). A quantity of frequency sub-spectra can be determinedbased on a target angular accuracy or computational limitations of theradar system 104.

The raw data 902 contains digital information (e.g., in-phase andquadrature data) for a period of time, different wavenumbers, andmultiple channels respectively associated with the receiving antennaelements 702. A Fast-Fourier Transform (FFT) 906 is performed on the rawdata 902 to generate pre-processed data 908. The pre-processed data 908includes digital information across the period of time, for differentranges (e.g., range bins), and for the multiple channels. A Dopplerfiltering process 910 is performed on the pre-processed data 908 togenerate range-Doppler data 912. The Doppler filtering process 910 maycomprise another FFT that generates amplitude and phase information formultiple range bins, multiple Doppler frequencies, and for the multiplechannels. The digital beamformer 616 produces beamforming data 914 basedon the range-Doppler data 912. The beamforming data 914 contains digitalinformation for a set of azimuths and/or elevations, which representsthe field of view for which different steering angles or beams areformed by the digital beamformer 616. Although not depicted, the digitalbeamformer 616 may alternatively generate the beamforming data 914 basedon the pre-processed data 908 and the Doppler filtering process 910 maygenerate the range-Doppler data 912 based on the beamforming data 914.To reduce a quantity of computations, the digital beamformer 616 mayprocess a portion of the range-Doppler data 912 or the pre-processeddata 908 based on a range, time, or Doppler frequency interval ofinterest.

The digital beamformer 616 can be implemented using a single-lookbeamformer 916, a multi-look interferometer 918, or a multi-lookbeamformer 920. In general, the single-look beamformer 916 can be usedfor deterministic objects (e.g., point-source targets having a singlephase center). For non-deterministic targets (e.g., targets havingmultiple phase centers), the multi-look interferometer 918 or themulti-look beamformer 920 are used to improve accuracies relative to thesingle-look beamformer 916. Humans are an example of a non-deterministictarget and have multiple phase centers 922 that can change based ondifferent aspect angles, as shown at 924-1 and 924-2. Variations in theconstructive or destructive interference generated by the multiple phasecenters 922 can make it challenging for conventional radar systems toaccurately determine angular positions. The multi-look interferometer918 or the multi-look beamformer 920, however, perform coherentaveraging to increase an accuracy of the beamforming data 914. Themulti-look interferometer 918 coherently averages two channels togenerate phase information that can be used to accurately determine theangular information. The multi-look beamformer 920, on the other hand,can coherently average two or more channels using linear or non-linearbeamformers, such as Fourier, Capon, multiple signal classification(MUSIC), or minimum variance distortion less response (MVDR). Theincreased accuracies provided via the multi-look beamformer 920 or themulti-look interferometer 918 enable the radar system 104 to recognizesmall gestures or distinguish between multiple portions of the user(e.g., facial features).

The angle estimator 618 analyzes the beamforming data 914 to estimateone or more angular positions. The angle estimator 618 may utilizesignal processing techniques, pattern matching techniques, or machinelearning. The angle estimator 618 also resolves angular ambiguities thatmay result from a design of the radar system 104 or the field of viewthe radar system 104 monitors. An example angular ambiguity is shownwithin an amplitude plot 926 (e.g., amplitude response).

The amplitude plot 926 depicts amplitude differences that can occur fordifferent angular positions of the target and for different steeringangles 810. A first amplitude response 928-1 (illustrated with a solidline) is shown for a target positioned at a first angular position930-1. Likewise, a second amplitude response 928-2 (illustrated with adotted-line) is shown for the target positioned at a second angularposition 930-2. In this example, the differences are considered acrossangles between −180 degrees and 180 degrees.

As shown in the amplitude plot 926, an ambiguous zone exists for the twoangular positions 930-1 and 930-2. The first amplitude response 928-1has a highest peak at the first angular position 930-1 and a lesser peakat the second angular position 930-2. While the highest peak correspondsto the actual position of the target, the lesser peak causes the firstangular position 930-1 to be ambiguous because it is within somethreshold for which conventional radars may be unable to confidentlydetermine whether the target is at the first angular position 930-1 orthe second angular position 930-2. In contrast, the second amplituderesponse 928-2 has a lesser peak at the second angular position 930-2and a higher peak at the first angular position 930-1. In this case, thelesser peak corresponds to the target's location.

While conventional radars may be limited to using a highest peakamplitude to determine the angular positions, the angle estimator 618instead analyzes subtle differences in shapes of the amplitude responses928-1 and 928-2. Characteristics of the shapes can include, for example,roll-offs, peak or null widths, an angular location of the peaks ornulls, a height or depth of the peaks and nulls, shapes of sidelobes,symmetry within the amplitude response 928-1 or 928-2, or the lack ofsymmetry within the amplitude response 928-1 or 928-2. Similar shapecharacteristics can be analyzed in a phase response, which can provideadditional information for resolving the angular ambiguity. The angleestimator 618 therefore maps the unique angular signature or pattern toan angular position.

The angle estimator 618 can include a suite of algorithms or tools thatcan be selected according to the type of UE 102 (e.g., computationalcapability or power constraints) or a target angular resolution for theradar manager 106. In some implementations, the angle estimator 618 caninclude a neural network 932, a convolutional neural network (CNN) 934,or a long short-term memory (LSTM) network 936. The neural network 932can have various depths or quantities of hidden layers (e.g., threehidden layers, five hidden layers, or ten hidden layers) and can alsoinclude different quantities of connections (e.g., the neural network932 can comprise a fully-connected neural network or apartially-connected neural network). In some cases, the CNN 934 can beused to increase computational speed of the angle estimator 618. TheLSTM network 936 can be used to enable the angle estimator 618 to trackthe target. Using machine-learning techniques, the angle estimator 618employs non-linear functions to analyze the shape of the amplituderesponse 928-1 or 928-2 and generate angular probability data 938, whichindicates a likelihood that the user or a portion of the user is withinan angular bin. The angle estimator 618 may provide the angularprobability data 938 for a few angular bins, such as two angular bins toprovide probabilities of a target being to the left or right of the UE102, or for thousands of angular bins (e.g., to provide the angularprobability data 938 for a continuous angular measurement).

Based on the angular probability data 938, a tracker module 940 producesangular position data 942, which identifies an angular location of thetarget. The tracker module 940 may determine the angular location of thetarget based on the angular bin that has a highest probability in theangular probability data 938 or based on prediction information (e.g.,previously-measured angular position information). The tracker module940 may also keep track of one or more moving targets to enable theradar system 104 to confidently distinguish or identify the targets.Other data can also be used to determine the angular position, includingrange, Doppler, velocity, or acceleration. In some cases, the trackermodule 940 can include an alpha-beta tracker, a Kalman filter, amultiple hypothesis tracker (MHT), and so forth.

A quantizer module 944 obtains the angular position data 942 andquantizes the data to produce quantized angular position data 946. Thequantization can be performed based on a target angular resolution forthe radar manager 106. In some situations, fewer quantization levels canbe used such that the quantized angular position data 946 indicateswhether the target is to the right or to the left of the UE 102 oridentifies a 90-degree quadrant the target is located within. This maybe sufficient for some radar-based applications, such as user proximitydetection. In other situations, a larger number of quantization levelscan be used such that the quantized angular position data 946 indicatesan angular position of the target within an accuracy of a fraction of adegree, one degree, five degrees, and so forth. This resolution can beused for higher-resolution radar-based applications, such as gesturerecognition, or in implementations of the attention state or theinteraction state as described herein. In some implementations, thedigital beamformer 616, the angle estimator 618, the tracker module 940,and the quantizer module 944 are together implemented in a singlemachine-learning module.

Among the advantages of the described implementations, includingimplementations in which radar is used to determine a user's intent toengage, disengage, or maintain engagement, and further includingimplementations in which radar is used to detect user action that iscategorized as an indication of a user intent to engage or interact withthe electronic device, either of which might alternatively be achievableusing the on-device camera that is provided with most modernsmartphones, is that the power usage of the radar system issubstantially less than the power usage of the camera system, while thepropriety of the results can often be better with the radar system thanwith the camera system. For example, using the radar system 104described hereinabove, the desired user-intention detection can beachieved at average power ranging from single-digit milliwatts to just afew dozen milliwatts (e.g., 10 mW, 20 mW, 30 mW or 40 mW), evenincluding the processing power for processing the radar vector data tomake the determinations. At these low levels of power, it would bereadily acceptable to have the radar system 104 enabled at all times. Assuch, for example, with the smartphone radar system 104 in thealways-enabled state, the desired delightful and seamless experiencepresently described can still be provided for a user that has beensitting across the room from their smartphone for many hours.

In contrast, the optical cameras provided with most of today'ssmartphones typically operate at hundreds of milliwatts of power (e.g.,an order of magnitude higher than 40 mW, which is 400 mW). At such powerrates, optical cameras would be disadvantageous because they wouldsignificantly reduce the battery life of most of today's smartphones, somuch so as to make it highly impractical, if not prohibitive, to havethe optical camera in an always-on state. An additional advantage of theradar system 104 is that the field of view can be quite large, readilyenough to detect a user walking up from any direction even when lyingflat and face-up on a table (for many typical implementations in whichthe radar chip is facing outward in the same general direction as theselfie camera) and, furthermore, by virtue of its Doppler processingability can be highly effective (especially at operating frequenciesnear 60 GHz) in detecting even relatively subtle movements of movingbodies from the variety of directions.

Additionally, the radar system 104 can operate in environments in whichthe performance of the camera system is reduced or restricted. Forexample, in lower-light environments, the camera system may have areduced ability to detect shape or movement. In contrast, the radarsystem 104 performs as well in lower light as in full light. The radarsystem 104 can also detect presence and gestures through some obstacles.For instance, if the smartphone is in a pocket of a jacket or pair ofpants, a camera system cannot detect a user or a gesture. The radarsystem 104, however, can still detect objects in its field, even througha fabric that would block the camera system. An even further advantageof using a radar system 104 over an onboard video camera system of asmartphone is privacy, because a user can have the advantages of theherein described delightful and seamless experiences while at the sametime not needing to be worried that there is a video camera taking videoof them for such purposes.

The entities of FIGS. 1, 2, 4, and 6-9 may be further divided, combined,used along with other sensors or components, and so on. In this way,different implementations of the UE 102, with different configurationsof the radar system 104 and the IMU 108, can be used to implementmaintaining an authenticated state. The example operating environment100 of FIG. 1 and the detailed illustrations of FIGS. 2-9 illustrate butsome of many possible environments and devices capable of employing thedescribed techniques.

Example Methods

This section illustrates example methods, which may operate separatelyor together in whole or in part. Various example methods are described,each set forth in a subsection for ease of reading; these subsectiontitles are not intended to limit the interoperability of each of thesemethods one with the other.

Authentication Management

FIG. 10 depicts an example method 1000 for managing authenticationthrough IMU and radar and is one example of managing power states for auser equipment. The method 1000 is shown as a set of blocks that specifyoperations performed but are not necessarily limited to the order orcombinations shown for performing the operations by the respectiveblocks. Further, any of one or more of the operations may be repeated,combined, reorganized, or linked to provide a wide array of additionaland/or alternate methods (e.g., methods 1200 and 1400). In portions ofthe following discussion, reference may be made to the example operatingenvironment 100 of FIG. 1 or to entities or processes as detailed inother figures, reference to which is made for example only. Thetechniques are not limited to performance by one entity or multipleentities operating on one device.

At 1002, an intent to engage of a user is determined, based on radardata and by a user equipment, the intent to engage indicating that theuser intends to engage with the user equipment. As noted above, theintent to engage can be indicated by determining that the user 120 isreaching toward the UE 102, looking at the UE 102, or leaning toward ororienting their body toward the UE 102, to name just three examples.

At 1004, alternatively or in addition to the determination of the intentto engage through the radar data, a movement of the user equipment isdetermined based on inertial data. This movement can indicate the user's120 picking up the UE 102, touching the UE 102, and other movements asnoted above.

At 1006, responsive to the determination of the intent to engage and, insome cases, the determination of movement of the user equipment, a powerstate of a power-consuming component of an authentication system isaltered. The power state of the power-consuming component is alteredfrom a first power state to a second power state, the second power stateconsuming greater power than the first power state. This alteration canbe based on solely the intent to engage determined using the radar dataor also through the movement determined through the inertial data.Furthermore, the power state of the power-consuming component can befurther raised or other components powered based on the movementdetermination. As noted above, this movement determination may confirmthe user's 120 intent to engage, also provide an intent to engage, orotherwise add speed and/or robustness to the determination to add power,resources, and so forth to the authentication system. Note that, in somecases, components of an authentication system remain powered even when auser has not been determined to be intending to engage. In such a case,the techniques act to perform an authentication process responsive tothe intent to engage being determined. In such a case latency is reducedeven if power is not conserved for that process. The techniques can,however, refrain from using resources not associated with theauthentication system, thereby conserving power in other ways.

The power state to which the power-consuming component of theauthentication system is altered may or may not be sufficient to enablethe authentication system to perform an authentication process on theuser. In some cases the second power state of the power-consumingcomponent is not the high-power state 504-1. In such a case, the secondpower state is the intermediate-power state 504-2 as noted above. Thisintermediate-power state 504-2, in some cases, is sufficient forperformance of the power-consuming component, such as a camera thatincludes an intermediate-power state that is still capable of providingsensor data for authentication without fully powering up (e.g.,capturing an image of a user in full light rather than in darkness,etc.). Another example is the display 116, which can be powered toaccept touch input for a password without powering the display'sluminosity to full power. Another case includes the radar system 104,where at a fairly close range of a user's face to the radar system 104,full power is not required to provide sufficiently-accurate facialfeatures to the authentication system 114.

In some cases, the powering up of the component is an intermediate step,such as a warm-up sequence, that may prepare the component or simplyreduce latency by giving the component additional time. In such a case,the state manager 112 can determine not to proceed to high power, suchas if an intent to disengage is determined prior to the component beingready to authenticate, the user 120 moving the UE 102 thereby preventingauthentication (e.g., into a pocket), and so forth. In some cases, thepowering is an intermediate step that is then fully powered responsiveto determining that the user 120 has moved the UE 102, illustrated at1004, and thus to a power sufficient to perform the authenticationprocess. This warm-up sequence powers the component to theintermediate-power state 504-2 and then, after some short period oftime, the component is powered sufficient to be used in theauthentication process (e.g., to the high-power state 504-1). In such acase, the component is at high power (or nearly so) while in apost-warm-up sequence following the warm-up sequence. For componentsthat consume substantial power if left on when not needed, but alsorequire a noticeable amount of time to increase power to a sufficientlevel for full functionality, such as some infrared or near-infrared(IR, NIR) sensors, an intermediate-power state during which a warm-upsequence is performed can save substantial power or reduce noticeableand potentially user-experience-damaging latency.

Example power-consuming components of an authentication system aredescribed above, such as face-unlock sensors 212 of the authenticationsystem 114 of FIG. 1, a touchscreen of the display 116, the radar system104, and the processor 608 (e.g., high-power processor 608-2). Forspecific details on the many potential power-consuming components of afacial-recognition system for authentication, see FIG. 2 and itsdescription.

At 1008, an authentication process is performed by the authenticationsystem. In doing so, the authentication system 114 uses thepower-consuming component at the altered power state, such as the secondpower state or a third, higher-power state. The authentication processis effective to authenticate the user or determine that the user is notauthenticated, indicating that access to the UE 102 should not bepermitted. As noted, the authentication process can be through facialrecognition, finger-print reading, password or other credential entrythrough a touch or audio interface (e.g., touch-screen data-entrycomponent of the display 116), and so forth. The authentication processcompares identifying features of the user or credentials with somesecure storage of comparable features or credentials to determine theuser's identity as authentic, and thus permitted access to the UE 102.This can be as simple as comparing a six-digit password entered throughthe display's touch screen, or require greater computations and systemcomplexity, such as determining facial features based on sensor datareceived from the power-consuming component and comparing the determinedfacial features to a facial-feature library. While not required, thisfacial-feature library can be stored local to the UE 102 and createdduring a facial-feature initialization by the UE 102 with theauthentication system 114. Furthermore, this library can be securelystored at the UE 102, such as in the form of an embedding on a securechip integral with the UE 102. This is one way in which privacy of theuser 120 can be maintained.

Throughout this disclosure examples are described where a computingsystem (e.g., the UE 102, a client device, a server device, a computer,or other type of computing system) may analyze information (e.g., radar,inertial, and facial-recognition sensor data) associated with a user,such as the just-mentioned facial features at operation 1008. Thecomputing system, however, can be configured to only use the informationafter the computing system receives explicit permission from the user ofthe computing system to use the data. For example, in situations wherethe UE 102 analyzes sensor data for facial features to authenticate theuser 120, individual users may be provided with an opportunity toprovide input to control whether programs or features of the UE 102 cancollect and make use of the data. The individual users may have constantcontrol over what programs can or cannot do with sensor data. Inaddition, information collected may be pre-treated in one or more waysbefore it is transferred, stored, or otherwise used, so thatpersonally-identifiable information is removed. For example, before theUE 102 shares sensor data with another device (e.g., to train a modelexecuting at another device), the UE 102 may pre-treat the sensor datato ensure that any user-identifying information or device-identifyinginformation embedded in the data is removed. Thus, the user may havecontrol over whether information is collected about the user and theuser's device, and how such information, if collected, may be used bythe computing device and/or a remote computing system.

Returning to the method 1000, at 1010, alternatively or in addition, thepower state of a display is altered responsive to determining that theuser equipment has moved or is moving. This alteration can be toincrease power sufficient to enable a touch-input reception capabilityof the display or to simply change the visual presentation of thedisplay. One example includes adding luminosity to the display 116 sothat, when a user touches the UE 102, the user sees that the UE 102 isaware of the user's intent and thus, presumably, is preparing to engagewith the user 120. Similarly, the UE 102 may do so responsive to theintent to engage determined at 1002.

In some cases, the authentication process is performed for some periodof time or iterations without success (e.g., some pre-set number or timeperiod). In such a case, the method 1000 can continue by re-performingthe authentication process or continue the process responsive to thedetermination of the movement at 1004, shown at 1012. This alternativeis shown with some of the dashed-line arrows in FIG. 10.

At 1014, responsive to the authentication process of the user at 1008(or re-performance at 1012) being successful, the user is authenticatedand an access state of the UE 102 is altered. This alteration canincrease the access of the UE 102 to high-access state from a low-, no-,or intermediate-access state, and in such a case, the UE 102 is“unlocked.” This high-access state (e.g., the high-access state 502-1 ofFIG. 5) is not required, however. Some levels of authentication canreserve access, power, or information for subsequent authentication.Examples include authenticating the user for use of some but not all ofthe applications and/or accounts of the UE 102 (e.g., accounts topurchase music, bank accounts, etc.), and requiring additionalauthentication for those reserved access accounts and applications. Forexample, in addition to the high-access state 502-1, the state manager112 can cause the UE 102 to be placed in the high-information state506-1. Examples of this alteration to the information state includepresenting a last-engaged-with application or webpage, including at alast-engaged-with portion, such as on page four of a ten-page article ona webpage, or half-way into a song or video that reproduces where theuser 120 was last engaged or authenticated with the UE 102. The statemanager 112 may alter these states quickly and seamlessly, responsive toauthentication of the user 120.

By way of example, consider one implementation that applies theapplication of method 1000 to scenario 1100 illustrated in FIG. 11. Thescenario 1100 includes five portions, each one chronologically followingthe prior portion. At a first portion of the scenario 1100, shown atscenario portion 1100-1, a user 1102 is not looking at, touching, orotherwise engaged with a smartphone 1104. Assume here that thesmartphone 1104 is in low-access, low-power, and low-information states502-3, 504-3, and 506-3, respectively (e.g., the smartphone 1104 looksoff, but has sufficient power to determine an intent to engage). Thisscenario portion 1100-1 is assumed to be the situation prior to theoperation of the method at 1002 in FIG. 10. A second portion is shown at1100-2, during which the user 1102 turns toward and looks at, but doesnot touch, the smartphone 1104. At this point, the techniques, atoperation 1002, determine, based on radar data, that the user 1102intends to engage with the smartphone 1104. This intent to engage isdetermined without use of a reach movement but is instead based on theuser 1102 looking toward and orienting their body toward the smartphone1104. The techniques make this determination through the radar manager106 at operation 1002, which passes the determination to the statemanager 112. Following this, the state manager 112, at operation 1006,alters a power state of a power-consuming component (the face-unlocksensor 212) of the authentication system 114. Note that this is donewell before the user reaches toward or picks up the smartphone 1104,reducing latency in causing the authentication system 114 to be ready toauthenticate the user.

Assume also, that over the next half of a second, while thepower-consuming component is powering up, the user 1102 moves closer to,and reaches toward the smartphone 1104 (the reach shown with hand 1106).This is shown at a third portion 1100-3. At this point theauthentication system 114 performs an authentication process (operation1008), but assume that the authentication process is unsuccessful forsome number of iterations and/or a period of time. The techniques maycease the attempts to authenticate the user 1102, and thereby savepower. Here, however, as shown at portion 1100-4, the user 1102 touchesthe smartphone 1104. This is determined, at operation 1004, to bemovement of the smartphone 1104 through inertial data sensed by the IMU108 of FIG. 1. This movement determination is passed to the statemanager 112. Based on this movement, the state manager 112 continues tocause the authentication system 114 to attempt to authenticate the user1102, as illustrated by operation 1012 of method 1000. Further still, atthe operation 1010, and also based on the movement, the state manager112 illuminates a display 1108 of the smartphone 1104. Thisillumination, or increasing a power level of the display 1108, can beperformed at the scenario portion 1100-2, 1100-3, or 11004, but here isshown responsive to determining the user's 1102 touch of the smartphone1104 (shown with time and notification information at 1110). By sodoing, the user 1102 is given feedback that the smartphone 1104 is awarethat they are intending to engage.

As noted, the state manager 112 causes the authentication system 114 tocontinue the authentication process and, through these continuedattempts, authenticates the user 1102. This is shown at portion 1100-5,resulting in the smartphone 1104 being at different states, high-access,high-power, and high-information states 501-1, 504-1, and 506-1,respectively, with the high-access state 502-1 shown with the display1108 presenting an unlock icon 1112. These state levels can be raisedautomatically by the state manager 112, providing a seamless userexperience for the user 1102.

In this example scenario 1100 the inertial data provided by the IMU 108causes the state manager 112 to ascertain, with a higher level ofconfidence and therefore justifying the additional power, that the user1102 intends to engage with the smartphone 1104 and therefore that theywant to be authenticated. This is but one example scenario showing howinertial data from an IMU and radar data from a radar system can be usedto authenticate a user quickly, easily, and with reduced powerconsumption.

Reducing High-Level States

FIG. 12 depicts an example method 1200 for reducing a high-level statethrough IMU and radar. The method 1200 is shown as a set of blocks thatspecify operations performed but are not necessarily limited to theorder or combinations shown for performing the operations by therespective blocks. Further, any of one or more of the operations may berepeated, combined, reorganized, or linked to provide a wide array ofadditional and/or alternate methods, including with other methods setforth in this document (e.g., methods 1000 and 1400). In portions of thefollowing discussion, reference may be made to the example operatingenvironment 100 of FIG. 1 or to entities or processes as detailed inother figures, reference to which is made for example only. Thetechniques are not limited to performance by one entity or multipleentities operating on one device.

Optionally, at 1202 and prior to operations 1204 or 1206, an inactivitytime period is determined to have expired. In contrast to some other,conventional techniques that rely solely on expiration of a time period,method 1200 may use or refrain from using an inactivity time period toreduce a high-level state for a user equipment. While this inactivitytimer is not required, use of a timer, even if a short timer, in somecases saves power. In more detail, an inactivity timer starts when alast user action with a user equipment is received, such as when a lasttouch to a touch screen or button, audio command, or gesture input wasreceived by the user equipment. Note that while some conventionaltechniques use a timer solely, and because of this conventional timersoften last minutes (e.g., one, three, five, or ten minutes), the method1200 can use a time period that is relatively short, such as one half,one, three, five, ten, or twenty seconds. By so doing, the likelihood ofthe user equipment exposing information, making inappropriate accessavailable, and so forth is very low, while use of a short inactivitytime period can operate to save some amount of power by refraining fromperforming operations of 1204 and/or 1206 for the inactivity timeperiod.

At 1204, a movement is determined, during a high-level state of a userequipment during which a user is interacting or has recently interactedwith the user equipment. The movement manager 110 determines thismovement based on inertial data received from the IMU 108, which isintegral with the UE 102. As shown with the dashed-lined arrow, thisoperation can optionally be responsive to operation 1206 and/or 1202(not shown). This determined movement can be one or more of the variousmovements set forth above, such a movement indicating that the user 120is picking up the UE 102, walking with, placing down, putting in apocket or enclosure, or simply touching near to or touching the UE 102.In some cases, the movement manager 110 determines that a movement is oris not sufficient to alter a state of the UE 102, and thus pass to thestate manager 112. Examples include those noted above, such as notovercoming a threshold movement, those caused by ambient vibrations, andthose that, while movement, are not a sufficient change to an ongoingmovement. Thus, the movement manager 110 can determine that the UE 102is moving as the user 120 walks along with the UE 102, but that movementcan be determined not to be a change sufficient to indicate a potentialthat the user 120 may be disengaging from the UE 102. Another way tolook at this is that movement can be based on a change and not simply acurrent moving of the UE 102. Example changes include moving and thennot moving, such as a user walking with the UE 102 and placing it downon a table. While the inertial data from the IMU 108 might not catch theuser 120 placing the UE 102 on the table, the determination that theinertial data shows little to no movement when there was movementimmediately prior (the user 120 walking with the UE 102) may still bedetermined as movement at operation 1204 based on this immediately-priormovement.

In more detail, the techniques can tailor a user equipment's state tothe user's engagement. Thus, in some cases the user equipment is in ahigh-level state (or states) due to the user being highly engaged withthe user equipment. For example, the method 1200 may determine prior tooperations 1204 or 1206 that the user is interacting with the userequipment. This determination of the user's engagement can be based onprior radar data indicating an intent to engage by the user, based onaudio or touch input from the user, a command or input received from theuser and through the audio or touch sensor, a successful authenticationprocess, and so forth.

At 1206, an intent to disengage is determined based on radar data and bythe user equipment. The radar manager 106 receives radar data from theradar system 104 and, using this radar data, determines whether the userintends to disengage from the UE 102. This intent to disengage includesthe various types set forth above, such as a hand retraction of the user120 from the UE 102, a facial orientation change relative to the UE 102,the user 120 turning away from or orienting their back to the UE 102,and so forth.

As shown with the dashed-lined arrow, this operation 1206 can optionallybe responsive to operation 1204 (and/or 1202, not shown). In these casesthe state manager 112 or the radar manager 106 acts to conserve power byrefraining from determining the user's 120 intent to disengage until themovement is determined, and vice-versa for the movement determination at1204. By so doing, power can be conserved. Thus, the power-managementmodule 620 can be directed by the techniques to keep the radar system104 at reduced power until the movement is determined at 1204. Oncemovement is determined, the state manager 112 causes thepower-management module 620 to increase power to the radar system 104 inpreparation to determine whether the user 120 is acting in a mannerindicating an intent to disengage.

At 1208, the high-level state of the user equipment is reduced to anintermediate-level or low-level state, responsive to the determinationof the movement and/or the intent to disengage. In more detail, see anexample high-level state 1208-1, which can be one or multiple statesinvolving access, power, or information, e.g., those illustrated in FIG.5 (the high-access state 502-1, the high-power 504-1, or thehigh-information state 506-1). The state manager 112, responsive todetermination of movement or an intent to disengage, or both, determinesto reduce one or more of the states of the UE 102. This is illustratedin FIG. 12 with arrows showing a reduction from the high-level 1208-1 toan intermediate level 1208-2 or a low level 1208-3. These are but two ofvarious granularities of power, access, and information. As illustratedin FIG. 5, the intermediate level 1208-2 and the low level 1208-3include the intermediate-access state 502-2, the intermediate-powerstate 504-2, and the intermediate-information state 506-2, each of whichis described above. The low level 1208-3 is illustrated with three lowstates, the low-access state 502-3, the low-power state 504-3, and thelow-information state 506-3. These states are described in detail above.Note that any one, two, or all three of these states can be reduced bythe state manager 112 at operation 1208, either each to a same level ordiffering levels. Thus, the state manager 112 may reduce the high-accessstate 502-1 to an intermediate or low state, and keep the power stateand the information state at high or a mix of levels. Similarly, thestate manager 112 may reduce the power state 504 to the low-power state504-3 while keeping the UE 102 at the high-access state 502-1 (e.g.,“unlocked”).

By way of example, consider the application of method 1200 to scenario1300 illustrated in FIG. 13. The scenario 1300 includes three portions,each one chronologically following the prior portion. Prior to the firstportion of the scenario 1300, assume that user 1302 is actively engagedwith smartphone 1304 and that the smartphone 1304 is in high-levelstates, namely power, access, and information states. At the firstportion, shown at scenario portion 1300-1, the user 1302 walks up to atable, and places the smartphone 1304 on the table. At operation 1204,the IMU 108 receives inertial data either for the touching of thesmartphone 1304 on the table or a lack of inertial data when, previousto being placed on the table, inertial data indicated movement (based onthe user 1302 walking with the smartphone 1304). Based on either or bothof these inertial data, the movement manager 110 determines a movementfor the smartphone 1304 and passes this determination to the radarmanager 106 and/or the state manager 112.

Assume that the radar manager 106 provides the radar field 118 (notshown for visual brevity, see FIG. 1 for an example) either immediatelyresponsive to the movement data or was already doing so, and thereforereceives radar data indicating the user's 1302 body position and soforth. Based on this radar data, the radar manager 106 determines for afirst iteration (and likely multiple others) that, at operation 1206 forthe body, arm, and hand placement, the user 1302 is not intending todisengage at the scenario portion 1300-1. This is due to the user 1302having a body orientation toward the smartphone 1304 and the user's handand arm being oriented toward the smartphone 1304. Because of this, ahigh-information state 1306-1 is not altered.

At the scenario portion 1300-2, however, assume that roughly two secondslater, the user 1302 picks up their coffee cup and begins to walk awaywhile turning their body away from the smartphone 1304. At this point,the radar manager 106 determines that the user 1302 is intending todisengage from the smartphone 1304 based on the body orientation of theuser 1302 being turned partly away from the smartphone 1304, and theuser's 1302 arm and hand oriented toward the coffee cup and not thesmartphone 1304. The radar manager 106 passes this determination to thestate manager 112.

At operation 1208, responsive to receiving the movement and intent todisengage determinations, the state manager 112 reduces the informationstate of the smartphone 1304 from the high-information state 1306-1shown at scenario portion 1300-1 to the intermediate-information state1306-2. These example information states are shown with informationdisplayed at scenario portion 1300-1 showing content from two textmessages and a time of day Immediately at the user 1302 turning theirbody and picking up their coffee cup, the information state is reducedto the intermediate-information state 1306-2, shown with the time of dayand reduced information about the text messages (shown with the name ofthe sender but no context). This intermediate amount of information canbe useful to the user 1302, as they may change their mind aboutengaging, or want to look back at the smartphone 1304 to see if a newnotification has arrived, such as a text from a different person.

Also or instead of showing the intermediate-information state 1306-2,and as part of operation 1208, the state manager 112 may proceed to alow level either immediately or after first being at an intermediatestate. Here assume that the state manager 112, responsive to additionaldeterminations by the radar manager 106 indicating that the user 1302intends to disengage or a higher confidence level thereof (e.g., hereshown with a high confidence as the user 1302 is now a few meters awayand has their back fully turned to the smartphone 1304), reduces theinformation state further to the low-information state 1306-3, shown asscenario portion 1300-3 presenting only a current time of day.

While this example shows changes to an information state, access andpower may also or instead be changed. This is shown in part with anunlock icon 1310 shown at scenario portion 1300-1, indicating a highlevel of access (e.g., the high-level access 502-1 of FIG. 5). At thescenario portion 1300-2 after the state manager 112 receives themovement data and the intent to disengage, the state manager 112 reducesthe access to a low level, which is indicated to the user with the lockicon 1312. Further still, power states can be altered, such as byreducing a luminosity of the smartphone's 1304 display (not shown) atthe scenario portions 1300-2 and/or 1300-3.

Maintaining an Authenticated State

FIG. 14 depicts an example method 1400 for maintaining an authenticatedstate. The method 1400 is shown as a set of blocks that specifyoperations performed but are not necessarily limited to the order orcombinations shown for performing the operations by the respectiveblocks. Further, any of one or more of the operations may be repeated,combined, reorganized, or linked to provide a wide array of additionaland/or alternate methods, including with other methods set forth in thisdocument (e.g., methods 1000 and 1200). In portions of the followingdiscussion, reference may be made to the example operating environment100 of FIG. 1 or to entities or processes as detailed in other figures,reference to which is made for example only. The techniques are notlimited to performance by one entity or multiple entities operating onone device.

Prior to discussing method 1400, note that any of the methods describedabove, in whole or in part, can be combined with method 1400. Consider,for example, the performance of method 1000 in FIG. 10. This method 1000describes one example of authentication management resulting inauthentication of a user of a user equipment. Responsive to thisauthentication, the user equipment enters into an authenticated state.This state is described in greater detail above. Thus, the method 1000(or some other manner of authentication of a user) is performed prior tomethod 1400.

At 1402, during an authenticated state of a user equipment, a potentialdisengagement by a user of the user equipment is determined. Thisdetermination of a potential disengagement by a user can includedetermining an intent to disengage by the user, as noted above, andother determinations set forth below. Also, as noted above, theauthenticated state permits access, by the user, of one or more of thedata, applications, functions, accounts, or components of the userequipment. Examples of an authenticated state include the high-accessstate 502-1 and the intermediate access state 502-2 noted in FIG. 5above. While either of these access states can be permitted by the UE102 when in the authenticated state (often based on a user preference oran operating system default setting), the authenticated state assumes aprevious authentication of the user. A user-selected preference orsetting, however, can permit a high or intermediate access of the UE 102without authentication. Thus, while the authenticated state may includeaccess permitted by the high and intermediate access states noted above,the high and intermediate access are not necessarily authenticatedstates.

As illustrated in FIG. 14, determination of the potential disengagementcan be performed, optionally, responsive to (or through performing)operation 1404 or operation 1406, as well as other manners describedherein, such as through determining an intent to disengage at operation1206 of method 1200. At 1404, expiration of an inactivity time period isdetermined. As noted above, this inactivity time period can start when alast user action is received, an active engagement with the userequipment ends (or is last received), or when a last intent to engagewas determined. For example, an inactivity timer (e.g., a time period)begins when a user last touches a touch-sensitive display or button, alast-received audio command is spoken, or a last-determinedtouch-independent gesture (e.g., a gesture determined using the radarsystem 104 noted above) is performed.

At 1406, a movement of the user equipment is determined based oninertial data of an inertial measurement unit (IMU) integral with theuser equipment. Example movements and inertial data are described above,such as inertial data received from the IMU 108 of FIG. 1. Thus, amovement determination is one way in which the method may determine thata user is potentially disengaging, such as by placing the UE 102 in alocker, bag, or pocket (though placing in a bag or pocket may later bedetermined to be a passive engagement, noted below).

At 1408, a passive engagement by the user with the user equipment isdetermined based on radar data. This determination of a passiveengagement can be responsive to determination at 1402 of the potentialdisengagement (shown with a dashed-line arrow), or it can be independentof, or coincident with, that determination. Performing operation 1408responsive to the determination of the potential disengagement can, insome cases, save power or reduce latency. For example, the method 1400may increase power to components of the radar system 104 (see also FIGS.6-1 and 6-2) responsive to the determination of a potentialdisengagement. This can save power as noted above or give additionaltime for the radar system 104 to prepare to determine whether the useris passively engaged with the radar system 104.

In the context of FIG. 1, the radar manager 106 determines that the user120 is passively engaged with the UE 102. This passive engagement can bedetermined by the radar manager 106 in multiple ways, which can beexclusive or overlap one with the other. For example, the radar manager106 can determine that the user is passively engaged based on the radardata indicating that a hand of the user 120 is holding the userequipment 102 at an orientation at which the display 116 of the userequipment 102 is maintained. Thus, if the user 120 is holding the UE 102steady (or steady enough to view content or permit another person toview content) the user 120 is passively engaged. Other examples ofdetermining passive engagement are described above, including the user120 looking at or orienting their body toward the UE 102.

Furthermore, the radar manager 106 can determine passive engagementbased on the radar data indicating that the user 120 is present, such asby being within two meters of the UE 102. Other distances can also orinstead be used, such as 1.5 meters, one meter, or even one half of onemeter. In effect, the radar manager 106 can determine that the user 120is passively engaged by being roughly within reach of the UE 102. Theradar manager 106 may do so explicitly by indicating that the user 120is passively engaged, or simply pass information indicating a distancefrom the UE 102, to the state manager 112. The state manager 112 thendetermines passive engagement based on the proximity of the user 120and, in some cases, context, such as other people (or lack thereof),whether or not the user 120 is in a vehicle (car, bus, train), at adesk, and so forth. A user sitting in their home, for example, may havea larger permitted distance than the user sitting in a crowded coffeeshop or train.

At 1410, responsive to the determination of the passive engagement bythe user with the user equipment, the authenticated state is maintained.This maintaining of the authenticated state can continue until anotherpotential disengagement is determined, or for some time period, afterwhich method 1400 can again be performed. One example of anauthenticated state is the high-access state 502-1 of FIG. 5. In manysituations this authenticated state is an unlock state for the UE 102,but in some other cases the authenticated state permits some but not allaccess to the UE 102, such as the above-described intermediate-accessstate 502-2.

This maintaining of the authenticated state for the UE 102 does notrequire that other states be maintained. For example, in cases where theuser 120 is within two meters of the UE 102, but may or may not belooking toward or oriented toward the UE 102, the state manager 112 canreduce a power state or information state of the UE 102, such as fromthe high-power state 504-1 and the high-information state 506-1 tointermediate or low power or information states noted in FIG. 5. If,however, the passive engagement includes the user looking at the UE 102,the power or information states can also be maintained, such as tocontinue to present, through the display 116, content to the user 120.

Optionally, the method 1400 can proceed to operation 1412, in which apresence or an intent to engage of a non-user is determined based onradar data. This radar data can be the same or later-received radardata, such as radar data from the radar system 104 received some numberof seconds or minutes after the radar data on which the passiveengagement was based. Thus, at 1412 the radar manager 106 determinesthat a non-user is present or intends to engage with the UE 102. If anon-user, therefore, reaches for the UE 102, or looks at the display 116of the UE 102, the radar manager 106 can determine this presence orintent, and pass it to the state manager 112.

At 1414, responsive to the determination that the non-user is present orintends to engage with the user equipment, the maintenance of theauthenticated state is ceased. Thus, if a non-user walks up, reachesfor, or looks at the display 116 of the UE 102, the state manager 112ceases to maintain the authenticated state (or activelyde-authenticates) the UE 102. Along with this cessation, the statemanager 112 may also reduce other states, such as an information stateeffective to reduce or eliminate information presented to the non-user.Assume, for example, that an authenticated user is reading a privateemail on the subway train. If a person sitting behind the user looks atthe display, possibly to read the private email, the state manager 112can lock the UE 102 and cease to display the private email. This can beperformed quickly and seamlessly, further improving the privacy of auser.

A 1416, optionally after ceasing to maintain the authenticated state,the method can be returned to the authenticated state responsive to adetermination that the non-user is no longer present or no longerintending to engage. Continuing the example above, when the non-user inthe subway train looks away from the display 116 of the UE 102, thestate manager 112 may re-authenticate the user 120 through anauthentication process or simply by switching back to the authenticationstate without re-authenticating. Thus, the user 120 can simply go backto the previous states immediately on cessation of the condition thatcaused the de-authentication. While some authentication processes, suchas the system and process described herein, are both fast andpower-efficient, not performing an authentication process can be fasterand more-power-efficient. On returning to the authenticated state, thestate manager 112 can return the information state to the prior leveland at content matching the content last presented to the user 120. Inthis example, when the non-user looks away, the display 116 presents theprivate email at a same location last presented by the UE 102 to theuser 120. By so doing, seamless management of authentication andimproved information privacy is provided to users. Note that a selectionby the user 120 can override operations of the techniques, such as auser selection to de-authenticate. In some cases, the user 120 simplyturns off the UE 102, which is permitted by the methods describedherein.

Consider another example illustrated in FIG. 15 through a scenario 1500.The scenario 1500 includes four portions. At a first portion 1500-1,assume that a user 1502 has been authenticated to the smartphone 1504,such as through credential or facial-feature analysis, and thus that thesmartphone 1504 is in an authenticated state 1506. This authenticatedstate 1506 allows the user 1502 access to the smartphone 1504, which isshown through the user 1502 accessing content of the smartphone 1504 bywatching a television program about volcanic eruptions.

The scenario 1500 is shown diverging along two different paths. In onepath an inactivity timer begins when the user 120 ceases to touch orprovide input to the smartphone 1504, which here is when they relax towatch the television program. In another case an inactivity timer canbegin or not, but a potential disengagement will be determined withoutits expiration. Thus, at scenario portion 1500-2, after three minutes ofinactivity, the inactivity timer expires. Returning to FIG. 14,operation 1402 determines that a potential disengagement by the user hasoccurred, due to the inactivity time period expiring at operation 1404.For the second path shown at scenario portion 1500-3, operation 1402determines that a potential disengagement by the user has occurred bydetermining, based on inertial data, that a movement of the smartphone1504 has occurred through performing operation 1406. The cause of thismovement is the user 1502 putting their foot on the edge of the table onwhich the smartphone 1504 is resting.

The radar manager 106, responsive to either of these determinations of apotential disengagement, determines, based on radar data, that the user1502 is passively engaged with the smartphone 1504. This operation isperformed at 1408. Here assume that the user's 1502 presence or theirlooking at the smartphone 1504 are determined, either of which indicatethat the user 1502 is passively engaged.

In response, at operation 1410, the state manager 112 maintains theauthenticated state. All of this can be performed seamlessly and withoutthe user 1502 noticing that it has been performed. As shown in scenarioportion 1500-4, the smartphone 1504 simply continues to present thetelevision program through either path.

Consider another scenario 1600 of FIG. 16, which can follow the scenario1500 or be an alternative, stand-alone scenario. The scenario 1600includes three scenario portions, in a first scenario portion 1600-1,the user 1502 is watching the television program about volcanoes,similarly to as shown in FIG. 15, here marked at content 1602 of thesmartphone 1504. The smartphone 1504 is in an authenticated state duringthis presentation of the program, such as the authenticated state 1506noted in FIG. 15.

At scenario portion 1600-2, however, a non-user 1604 sits down on thecouch with the user 1502. This non-user 1604 is a colleague of the user1502 and so the user 1502 turns their head to them and begins talking tothem. These actions of the user 1502 can be considered a potentialdisengagement, either turning their head or talking or both, as notedabove. If considered a potential disengagement by the user 1502, thestate manager 112 reduces the state of the smartphone 1504, such as toreduce the access state or the information state, noted in FIGS. 5 and12 (e.g., operations 1206 and 1208 of method 1200).

Assume, however, that the radar manager 106 determines, throughoperation 1412 of method 1400 and based on radar data, the presence ofthe non-user 1604. Based on this presence of the non-user 1604, thestate manager 112 ceases to maintain the authenticated state 1506 afterthe state manager 112 previously acted to maintain the authenticatedstate of the smartphone 1504 (e.g., through operation 1410 shown in FIG.15). Thus, the state manager 112 can cause the smartphone 1504 to bereduced to a non-authenticated state 1604, shown at an expanded view ofthe scenario portion 1600-2. This change is shown to the user 1502through a lock icon 1606, as well as by ceasing to present the content1602.

At scenario portion 1600-3, the non-user 1604 has left and the user 1502returns to looking at the smartphone 1504. The radar manager 106determines that the non-user 1604 is no longer present, indicates thisdetermination to the state manager 112, which then returns thesmartphone 1504 to the authenticated state 1506. Note that the statemanager 112 may also require a determination that the user 1502 isintending to engage with the smartphone 1504, or may simply return tothe authenticated state based on the non-user 1604 leaving the presenceof the smartphone 1504. Note also that the techniques described in thisdocument can return a user to the spot at which they left off,seamlessly, thereby providing an excellent user experience. This isshown in FIG. 16 with the state manager 112 returning the smartphone1504 to a same television program and at a same or nearly a same pointthat was last presented to the user 1502. For some embodiments thetechniques allow the user, in a setup screen or similar deviceconfiguration screen, to dictate whether, at step 1416, the smartphone1504 will return to the authenticated state responsive to thedetermination that the non-user is no longer present or intending toengage, versus whether the smartphone 1504 will stay in anon-authenticated state until a more-rigorous authentication processusing a power-consuming component of an authentication system (e.g.,step 1006, supra) is carried out. Stated differently, the techniques canprovide a user-selected setting, through a setup or similar deviceconfiguration, that causes the smartphone 1504 to remainde-authenticated once there has been the taint of a non-user, even ifthe taint is no longer there.

EXAMPLES

In the following section, examples are provided.

Example 1: A method comprising: determining, during an authenticatedstate of a user equipment, a potential disengagement by the user of theuser equipment, the authenticated state permitting access by the user ofdata, applications, functions, accounts, or components of the userequipment; determining, based on radar data and by the user equipment, apassive engagement by the user with the user equipment; and responsiveto the determination of the passive engagement by the user with the userequipment, maintaining the authenticated state.

Example 2: The method of example 1, wherein the authenticated statepermits access by the user to the data, the applications, the functions,at least one of the accounts, and at least one of the components of theuser equipment.

Example 3: The method of examples 1 or 2, further comprising determiningthat an inactivity time period has expired and wherein determining thepotential disengagement is based on the determination that theinactivity time period has expired.

Example 4: The method of example 3, wherein the inactivity timer periodbegins at a last user action with the user equipment, a last activeengagement with the user equipment, or a last-determined intent toengage with the user equipment.

Example 5: The method of examples 1 or 2, further comprisingdetermining, based on inertial data of an inertial measurement unit(IMU) integral with the user equipment, a movement of the userequipment, and wherein determining the potential disengagement is basedon the determined movement.

Example 6: The method of any of the preceding examples, whereindetermining the passive engagement by the user with the user equipmentis responsive to the determination of the potential disengagement andfurther comprising, prior to determining the passive engagement by theuser, increasing a power state of a component of a radar system fromwhich the radar data is received.

Example 7: The method of any of the preceding examples, whereindetermining passive engagement by the user determines, based on theradar data, that a hand of the user is holding the user equipment at anorientation at which a display of the user equipment is maintained.

Example 8: The method of any of examples 1 through 6, whereindetermining passive engagement by the user of the user equipmentdetermines, based on the radar data, that the user is oriented toward orlooking toward the user equipment.

Example 9: The method of examples 1 through 6, wherein determiningpassive engagement by the user of the user equipment determines, basedon the radar data, that the user is within two meters of the userequipment.

Example 10: The method of any of the preceding examples, furthercomprising reducing an information state of the user equipment from ahigh-information state to an intermediate-information state or alow-information state.

Example 11: The method of example 10, wherein reducing the informationstate is responsive to determining that the user is oriented or lookingaway from the user equipment.

Example 12: The method of any of the preceding examples, furthercomprising determining, based on the radar data or later-received radardata, an intent to engage or a presence of a non-user and, responsive tothe determination of the intent to engage or the presence, ceasing tomaintain the authenticated state.

Example 13: The method of example 12, further comprising returning tothe authenticated state responsive to determining that the non-user isno longer present.

Example 14: The method of example 13, further comprising, responsive tothe determination of the intent to engage or the presence of thenon-user, reducing an information state of the user equipment and,responsive to returning to the authenticated state, increasing theinformation state of the user equipment.

Example 15: The method of example 14, wherein increasing the informationstate of the user equipment presents information as presented prior tothe reduction of the information state.

Example 16: An apparatus configured to perform a method of any one ofexamples 1 through 15.

Conclusion

Although implementations of techniques for, and apparatuses enabling,maintaining an authenticated state have been described in languagespecific to features and/or methods, it is to be understood that thesubject of the appended claims is not necessarily limited to thespecific features or methods described. Rather, the specific featuresand methods are disclosed as example implementations enablingmaintaining an authenticated state.

What is claimed is:
 1. A method comprising: determining, during anauthenticated state of a user equipment, a potential disengagement bythe user of the user equipment, the authenticated state permittingaccess by the user of data, applications, functions, accounts, orcomponents of the user equipment; determining, based on radar data andby the user equipment, a passive engagement by the user with the userequipment; and responsive to the determination of the passive engagementby the user with the user equipment, maintaining the authenticatedstate.
 2. The method of claim 1, wherein the authenticated state permitsaccess by the user to the data, the applications, the functions, atleast one of the accounts, and at least one of the components of theuser equipment.
 3. The method of claim 1, further comprising determiningthat an inactivity time period has expired and wherein determining thepotential disengagement is based on the determination that theinactivity time period has expired.
 4. The method of claim 3, whereinthe inactivity timer period begins at a last user action with the userequipment, a last active engagement with the user equipment, or alast-determined intent to engage with the user equipment.
 5. The methodof claim 1, further comprising determining, based on inertial data of aninertial measurement unit (IMU) integral with the user equipment, amovement of the user equipment, and wherein determining the potentialdisengagement is based on the determined movement.
 6. The method ofclaim 1, wherein determining the passive engagement by the user with theuser equipment is responsive to the determination of the potentialdisengagement and further comprising, prior to determining the passiveengagement by the user, increasing a power state of a component of aradar system from which the radar data is received.
 7. The method ofclaim 1, wherein determining passive engagement by the user determines,based on the radar data, that a hand of the user is holding the userequipment at an orientation at which a display of the user equipment ismaintained.
 8. The method of claim 1, wherein determining passiveengagement by the user of the user equipment determines, based on theradar data, that the user is oriented toward or looking toward the userequipment.
 9. The method of claim 1, wherein determining passiveengagement by the user of the user equipment determines, based on theradar data, that the user is within two meters of the user equipment.10. The method of claim 1, further comprising reducing an informationstate of the user equipment from a high-information state to anintermediate-information state or a low-information state.
 11. Themethod of claim 10, wherein reducing the information state is responsiveto determining that the user is oriented or looking away from the userequipment.
 12. The method of claim 1, further comprising determining,based on the radar data or later-received radar data, an intent toengage of a non-user or a presence of the non-user and, responsive tothe determination of the intent to engage of the non-user or thepresence of the non-user, ceasing to maintain the authenticated state.13. The method of claim 12, further comprising returning to theauthenticated state responsive to determining that the non-user is nolonger present.
 14. The method of claim 13, further comprising,responsive to the determination of the intent to engage of the non-useror the presence of the non-user, reducing an information state of theuser equipment and, responsive to returning to the authenticated state,increasing the information state of the user equipment.
 15. The methodof claim 14, wherein increasing the information state of the userequipment presents information as presented prior to the reduction ofthe information state.
 16. An apparatus configured to: determine, duringan authenticated state of the apparatus and by at least one of a radarmanager, a movement manager, and a state manager, a potentialdisengagement by the user of the apparatus, the authenticated statepermitting access by the user of data, applications, functions,accounts, or components of the apparatus; determine, based on radar dataand by the radar manager, a passive engagement by the user with theapparatus; and responsive to the determination of the passive engagementby the user with the apparatus, maintain the authenticated state. 17.The apparatus of claim 16, wherein the determination of the passiveengagement by the user with the apparatus is responsive to thedetermination of the potential disengagement; and the apparatus furtherconfigured to, prior to the determination of the passive engagement bythe user, increase a power state of a component of a radar system fromwhich the radar data is received.
 18. The apparatus of claim 16, whereinthe apparatus is configured to, in determining passive engagement by theuser with the apparatus, determine, based on the radar data, that theuser is within two meters of the apparatus.
 19. The apparatus of claim16, wherein the apparatus is further configured to reduce, responsive toa determination that the user is oriented or looking away from theapparatus, an information state of the apparatus from a high-informationstate to an intermediate-information state or a low-information state.20. The apparatus of claim 16, further configured to determine, based onthe radar data or later-received radar data, an intent to engage of anon-user or a presence of the non-user and, responsive to thedetermination of the intent to engage of the non-user or the presence ofthe non-user, ceasing to maintain the authenticated state.